JP2023506182A - Reduced interference in the received signal caused by simultaneous transmission signals in the same frequency band as the received signal - Google Patents

Abstract

In one embodiment, a remote antenna unit includes a transmitter, a receiver, an antenna array, and first and second interference circuits. The transmitter is configured to generate at least one transmitted signal and the receiver is configured to process at least one received signal. the antenna array includes one or more antennas, each of at least one of the one or more antennas coupled to the transmitter and responsive to a respective one of the at least one transmit signal; each of the at least one or more antennas configured to radiate a respective downlink signal, each one of the at least one received signal coupled to a receiver and responsive to the uplink signal; configured to generate one And first and second interference circuits are coupled to the transmitter and receiver, respectively, and each are configured to reduce interference in each of the at least one received signal.

Description

CROSS REFERENCE TO RELATED APPLICATIONS This application is a U.S. Provisional Patent Application entitled "REDUCE, IN A RECEIVE SIGNAL, INTERFERENCE CAUSED BY SIMULTANEOUS TRANSMIT SIGNAL IN A SAME FREQUENCY BAND AS THE RECEIVE SIGNAL," filed December 13, 2019. No. 62/948,024, the entirety of which is incorporated herein by reference.

FIG. 1 is a block diagram of a distributed antenna system (DAS) 10 configured for coupling to one or more base stations 12 and including one or more remote antenna units 14 . Typically, each base station 12 serves and is controlled by a particular mobile operator, such as T-Mobile®, Verizon®, or ATT®, and has a remote antenna unit. configured to receive uplink signals and transmit downlink signals via one or more of 14; For example, each base station 12 receives uplink signals via all of the remote antenna units 14 so that each mobile operator is provided with the full signal coverage area in which the DAS 10 is configured to function. It may be configured to transmit downlink signals.

According to standards such as the 5G New Radio (5GNR) standard, which calls the DAS 10 to operate in a radio access network (RAN) where the uplink-downlink patterns of multiple signals may change dynamically and not be synchronized with each other. When operated, the antenna 16 of one remote antenna unit 14, that antenna, or another antenna on the same or a different remote antenna unit, operates on the same frequency band as the uplink, or even on one or more of the same carrier frequencies. Uplink signals may be received at the same time that downlink signals are being transmitted. In conventional TDD mode, the DAS 10 will switch between Tx and Rx. That is, in conventional TDD mode, the uplink and downlink patterns of all TDD signals in the band switch between Tx/Rx synchronously with the predictable pattern of the synchronized TDD signals carried by DAS 10. As DAS 10 operates, it is static and synchronized. In contrast, in newer standards such as 5GNR, the in-band TDD signals are dynamically changing and are not necessarily synchronized with each other, hence in this case it applies to all channels. Because there is no predictable Tx/Rx pattern to follow, it becomes difficult at best to operate DAS 10 in conventional TDD mode.

Unfortunately, if the antenna 16 of the remote antenna unit 14 is receiving an uplink signal at the same time that the antenna, or another antenna on the same or a different remote antenna unit, is transmitting a downlink signal, the uplink A received signal generated by an antenna in response to a signal may be a transmitted signal driving the antenna or interference resulting from one or more downlink signals transmitted by one or more other nearby antennas (e.g., non-linear distortions such as adjacent channel noise and amplifier noise).

Transmit interference in the received signal because the transmitted signal that excites the receive antenna 16 and one or more downlink signals transmitted by one or more other antennas are much stronger at the receive antenna than the uplink signal typically "swamps" the uplink component of the received signal.

For example, a 100 milliwatt (mW) signal with a channel leakage power ratio (ACLR) of −45 dBc is transmitted simultaneously on adjacent channels while the receiver coupled to receive antenna 16 has 5 dB of noise on the received signal. To achieve the index with an uplink channel bandwidth of 5 MHz, it is expected that remote antenna units 14 would need to be configured to reduce the total effective transmit interference power in the uplink channel by approximately 77 dB.

Therefore, there is a need for isolation and interference cancellation circuitry configured to reduce to acceptable levels transmit interference in received signals generated by remote antenna units 14 of DAS 10 operating in radio access networks, and A need has also arisen for a remote antenna unit incorporating such circuitry.

In one embodiment, a remote antenna unit capable of meeting the features described above includes a transmitter or portion thereof, a receiver or portion thereof, an antenna array, and first and second interference circuits. include. The transmitter, or portion thereof, is configured to generate at least one transmitted signal and the receiver, or portion thereof, is configured to process at least one received signal. For example, as used herein, "transmitter" and "receiver" may be divided between a host location (e.g., base station 12 or master unit 18) and remote antenna unit 14, transmitting or It is understood to mean at least part of the receive chain. For example, generation (modulation) and processing (demodulation) may occur back at base station 12 rather than at remote antenna unit 14 . In one example, the remote antenna unit 14 includes RF front-end circuitry, which may include, for example, a digital-to-analog converter (DAC), an upconverter, and a power amplifier on the downlink path, and a low frequency signal on the uplink path. It may include noise amplifiers, downconverters, and analog-to-digital converters (ADCs). The antenna array includes one or more antennas, each of at least one of the one or more antennas coupled to the transmitter and responsive to a respective one of the at least one transmitted signal. each of the at least one or more antennas coupled to a receiver and responsive to the uplink signal to radiate a respective downlink signal from the at least one received signal; configured to generate one of each. and first and second interfering circuits are respectively coupled to the transmitter and receiver, and in each of the at least one received signal, at least one transmitted signal, one or more on the same remote antenna unit; at least one downlink signal radiated by one of the antennas and at least one interfering one radiated by one or more other antennas on one or more other remote antenna units Each configured to reduce interference caused by one or more of the downlink signals.

For example, such a remote antenna unit may include multiple different interference reduction circuits that together provide an appropriate level of interference reduction for received signals.

Further by way of example, one of the interference reduction circuits may reduce received signals from the same antenna where the transmitted and received signals overlap at least partially in time and where the interference includes passive intermodulation (PIM). It may be an isolation circuit configured to isolate the transmitter from the receiver to reduce interference caused by the transmitted signal to the antenna.

In yet a further example, one of the interference reduction circuits is configured to transmit from the received signal to the same antenna, or the same or different signal where the transmitted signal or downlink signal at least partially overlaps the received signal in time. It may be an analog interference cancellation circuit configured to provide first order linear correction by canceling downlink signals from adjacent antennas on remote antenna units.

In a still further example, one of the interference cancellation circuits can be a digital interference cancellation circuit configured to provide first order linear and non-linear corrections to the received signal. A digital interference cancellation circuit may provide first-order linear correction to the received signal in the same manner as the analog interference cancellation circuit described above, and, for example, out-of-band distortion that may still be close enough to the frequency of the received signal. (also called frequency sidebands and frequency "skirts"), thereby canceling out-of-band distortion from the received signal, which is difficult to reduce to acceptable levels with conventional filtering can provide non-linear correction.

In still yet further examples, each of one or more of the interference reduction circuits may include one or more control loops, two or more of the interference reduction circuits forming or otherwise forming control loops. If not, it can be part of it. For example, a digital interference cancellation circuit may use negative feedback to control the parameters of the isolation circuit to further reduce the level of transmit interference in the received signal.

1 is a diagram of a distributed antenna system (DAS), a base station coupled to the DAS, and user equipment configured to communicate with the DAS and the base station via the DAS; FIG. FIG. 2 is a diagram of a portion of the remote antenna unit of FIG. 1, partly including circuitry configured to reduce interference in signals received from the antennas caused by simultaneously transmitting signals to the same antenna, according to one embodiment; include. FIG. 2 is a diagram of a portion of the remote antenna unit of FIG. 1, partly including circuitry configured to reduce interference in signals received from the antennas caused by simultaneously transmitting signals to the same antenna, according to one embodiment; include. 2 is a diagram of a portion of the remote antenna unit of FIG. 1 , partially showing interference in the received signal from the antenna caused by simultaneous transmission signals to the same antenna and one on the same remote antenna unit, according to one embodiment. and interference caused by one or more downlink signals from the other antennas. FIG. 2 is a diagram of a portion of the remote antenna unit of FIG. 1, a portion of which in the received signal from the antenna is caused by simultaneous transmission signals to the same antenna and over one or more different remote antenna units, according to one embodiment. circuitry configured to reduce interference caused by one or more downlink signals from one or more other antennas of the . 2 is a diagram of a portion of the remote antenna unit of FIG. 1, a portion of which in received signals from the antennas is caused by simultaneous transmission signals to the same antenna and the same or one or more different remote antennas, according to one embodiment. It includes circuitry configured to reduce interference caused by one or more downlink signals from one or more other antennas on the unit. FIG. 7 is a diagram of the transmit/receive isolation circuitry of FIGS. 2-6, according to one embodiment; FIG. 7 is a diagram of the transmit/receive isolation circuitry of FIGS. 2-6, according to one embodiment; 9 is a graph of transmit insertion loss versus frequency for the transmit/receive split circuit of FIG. 8, according to one embodiment; 9 is a graph of receive insertion loss versus frequency for the transmit/receive split circuit of FIG. 8, according to one embodiment; 8 is a graph of the isolation provided by the transmit/receive isolation circuit of FIG. 8 between the transmitter and receiver of FIGS. 2-6, against frequency, according to one embodiment. Transmitter-to-antenna insertion loss, transmit-receive isolation provided for transmitter-to-antenna insertion loss by the transmitter-receiver isolation circuit of FIG. 8, and by one of the circulators of FIG. 8, according to one embodiment. 2 is a graph comparing different transmitter-receiver separations. FIG. 7 is a diagram of the transmit/receive isolation circuitry of FIGS. 2-6, according to one embodiment; 14 is a graph of transmitter-to-antenna insertion loss, antenna-to-receiver insertion loss, and the transmit-receive isolation provided by the transmit-receive isolation circuit of FIG. 13, according to one embodiment; Transmitter-to-antenna insertion loss, transmit-receive isolation provided for transmitter-to-antenna insertion loss by the transmitter-receiver isolation circuit of FIG. 13, and by one of the circulators of FIG. 13, according to one embodiment. 2 is a graph comparing different transmitter-receiver separations. FIG. 7 is a diagram of the transmit/receive isolation circuitry of FIGS. 2-6, according to one embodiment; FIG. 2 is a diagram of a portion of the remote antenna unit of FIG. 1, partly including circuitry configured to reduce interference in signals received from the antennas caused by simultaneously transmitting signals to the same antenna, according to one embodiment; include. 2 is a diagram of a portion of the remote antenna unit of FIG. 1, where the remote antenna unit includes separate transmit and receive antennas, according to one embodiment; FIG. FIG. 2 is a diagram of a portion of the remote antenna unit of FIG. 1, the remote antenna unit for each of the one or more operators, each transmitter and receiver coupled to a receiver having a switch, according to one embodiment; Includes receiving antenna.

As used herein, “approximately,” “substantially,” and like words mean that a given quantity b is within b±10% of b, or |10% of b. A value of 1 indicates that it can be in the range of b±1. As used herein, “approximately,” “substantially,” and like words also mean that the range b to c is from b−0.10(c−b) to c+0.10(c−b) can be As used herein with respect to the planarity of a surface or other region, "approximately", "substantially" and like words refer to the thickness between the highest and lowest points of the surface/region. difference does not exceed 0.20 millimeters (mm).

As explained above, FIG. 1 is a diagram of DAS 10 coupled to one or more base stations 12 and including one or more remote antenna units 14 .

In an embodiment, one or more of the remote antenna units 14 are induced in one or more received signals by one or more respective transmitted signals to the same antenna and the same remote antenna unit or one or more may be configured to reduce interference caused by one or more downlink signals from antennas on different remote antenna units.

Remote antenna units 14 of DAS 10 are typically located within buildings (e.g., office buildings, warehouses, malls, sports complexes) or outdoor areas (e.g., stadiums, downtowns, outdoor event venues, parks, beaches). or distributed around it to provide wireless coverage so that people can use their wireless devices (eg, smart phones, tablets, laptops) while within the building or outdoor area. Examples of the types of wireless coverage a DAS can provide include Wi-Fi, cellular service, and the many available Long Term Evolution (LTE) frequency bands (e.g., B1, B3, B7, B25, and B66). And, the frequency range in which DAS 10 may be configured to operate is, for example, approximately 600 MHz to 71 GHz. For example, DAS 10 may be configured to operate in the 5GNR frequency band from approximately 3.4 GHz to 3.8 GHz.

In addition to remote antenna units 14 , DAS 10 is coupled to or includes one or more master units 18 that are communicatively coupled to remote antenna units 14 . Further, in an embodiment, DAS 10 includes a digital DAS, and DAS traffic is distributed between master unit 18 and remote antenna units 14 in digital form. In other embodiments, DAS 10 is implemented, at least in part, as an analog DAS, with DAS traffic distributed over at least a portion of the path between master unit 18 and remote antenna units 14 in analog form.

Each master unit 18 is also communicatively coupled to one or more base stations 12 . One or more of base stations 12 may coexist with each master unit 18 to which it is coupled (eg, base station 12 is dedicated to providing base station capacity to DAS 10). Also, one or more of the base stations 12 may be located remotely from the respective master unit 18 to which it is coupled (eg, the base stations 12, in addition to providing capacity to the DAS 10, may is a macro base station that provides base station capacity for In this latter case, master unit 18 may be coupled to a donor antenna (not shown in FIG. 1) for communicating wirelessly with remotely located base station 12 . Further, one or more of the one or more base stations 12 each have attenuators, combiners, splitters, amplifiers, filters, cross-connects, etc., each of which is referred to as a respective point-of-interface (POI) circuit 20 . can be coupled to the master unit 18 using the respective networks of . This is done so that the desired set of RF carriers output by the base station 12 can be extracted, combined and routed to the appropriate master unit 18 on the downlink, and output by the master unit 18 on the uplink. A set of desired carriers to be used can be extracted, combined, and routed to the appropriate interface of each base station.

Base stations 12 may each be implemented as respective conventional monolithic base stations. Also, base stations 12 may each be a distributed base in which a baseband unit (BBU) (not shown in FIG. 1) is coupled to one or more remote radio heads (RRHs) (not shown in FIG. 1). It can be implemented using a station architecture, the fronthaul between the BBU and the RRH uses a stream of digital IQ samples. Examples of such approaches are described in the Common Public Radio Interface (CPRI), Open Base Station Architecture Initiative (OB SAI), and Open RAN (O-RAN) family of specifications, which are incorporated herein by reference. ing.

Master units 18 may each be configured to use a broadband or narrowband interface to base station 12 . Also, master units 18 may each interface with base station 12 using an analog radio frequency (RF) interface or a digital interface (eg, using a CPRI, OBSAI, or O-RAN digital interface). can be configured.

Conventionally, each master unit 18 uses analog radio frequency signals that each base station communicates to and from user equipment (e.g., smart phones, tablets, laptops) 22 using a suitable air interface standard. to interface with each base station 12 . DAS 10 operates as a distributed repeater for such radio frequency signals. RF signals transmitted from each base station 12 (also referred to herein as “downlink RF signals”) are received by one or more master units 18 . Each master unit 18 uses the downlink RF signal to generate downlink transport signals that are distributed to one or more of the remote antenna units 14 . Each such remote antenna unit 14 receives a downlink transport signal, reconstructs a version of the downlink RF signal based on the downlink transport signal, and transmits the reconstructed downlink RF signal to its remote antenna unit 14 . Radiated from at least one antenna array 16 included in or otherwise coupled to the antenna unit.

A similar process is performed for the uplink direction. RF signals transmitted from user equipment 22 (also referred to herein as “uplink RF signals”) are received at one or more remote antenna units 14 . Each remote antenna unit 14 uses the uplink RF signal to generate an uplink transport signal that is transmitted from the remote antenna unit 14 to the master unit 18 . Each master unit 18 receives uplink transport signals transmitted from one or more remote antenna units 14 coupled to it. The master unit 18 combines data or signals communicated via uplink transport signals received at the master unit to reconstruct a version of the uplink RF signal received at the remote antenna unit 14 . Master unit 18 communicates the reconstructed uplink RF signal to one or more base stations 12 . In this manner, the signal and communication coverage of base station 12 may be extended using DAS 10 .

One or more intermediate units 24 (some of which are also referred to herein as “expansion units”) may be positioned between the master unit 18 and one or more of the remote antenna units 14 . This may be done, for example, to increase the number of remote antenna units 14 that a single master unit 18 may serve, to increase the distance from the master unit to the remote unit, and/or to link the master unit to its association. can be done to reduce the amount of wiring required to connect to the remote antenna unit.

As noted above, DAS 10 may be implemented as a "digital" DAS. In a “digital” DAS, signals received from and provided to base stations 12 and user equipment 22 are digital in-phase (I) and quadrature (I) signals communicated between master unit 18 and remote antenna unit 14 . Q) Used to generate samples. This digital IQ representation of the original signal received from the base station 12 and from the user equipment 22 conveys telephone or data information according to the cellular air interface protocol used for wireless communication between the base station and the user equipment. Note that we still maintain the original modulation (ie, changes in carrier amplitude, phase, or frequency) used to do so. Examples of such cellular air interface protocols are, for example, 5GNR, Global System for Mobile Communications (GSM), Universal Mobile Telecommunications System (UMTS), and Long Term Evolution (LTE) air interface protocols. mentioned. Each stream of digital IQ samples also represents or includes a portion of the radio spectrum. For example, the digital IQ samples may represent a single radio access network carrier (e.g., a 5 MHz UMTS or LTE carrier) onto which voice or data information is modulated using the UMTS or LTE air interface. there is However, each such stream may also represent multiple carriers (eg, bands of the frequency spectrum or subbands of a given band of the frequency spectrum).

Additionally, one or more of the master units 18 interface with one or more base stations 12 using analog RF interfaces (eg, via either conventional monolithic base stations 12 or RRH analog RF interfaces). can be configured to As explained above, the base station 12 also includes a network of attenuators, combiners, splitters, amplifiers, filters, cross-connects, etc. (collectively referred to as "points of interface" or "POIs" 20). ) may be used to connect to the master unit 18 . This is done so that on the downlink the set of desired RF carriers output by the base station 12 can be extracted, combined and routed to the appropriate master unit 18, and on the uplink output by the master unit. A set of desired carriers can be extracted, combined, and routed to the appropriate interface of each base station.

Each master unit 18 downconverts the received signal to an intermediate frequency (IF) or baseband, digitizes the downconverted signal to produce the actual digital samples, and the actual digital samples. to generate digital in-phase (I) and quadrature (Q) samples to generate digital IQ samples from an analog radio signal received at radio frequency (RF). These digital IQ samples may also be filtered, amplified, attenuated, and/or resampled or decimated to lower sample rates. Digital samples can be generated in other ways. Each stream of digital IQ samples represents a portion of the radio frequency spectrum output by one or more base stations 12 . Each portion of the radio frequency spectrum may include, for example, a band of the radio spectrum, subbands of a given band of the radio spectrum, or individual radio carriers.

Similarly, in the uplink, each master unit 18 digitally combines streams of digital IQ samples representing the same carrier or frequency band or subband (e.g., by digitally adding such digital IQ samples), digitally upconverting the synthesized digital IQ samples to produce real digital samples; performing a digital-to-analog process on the real digital samples to produce an IF or baseband analog signal; Uplink analog radio signals from one or more streams of digital IQ samples received from one or more remote antenna units 14 by upconverting the IF or baseband analog signals to the desired RF frequency. obtain. Digital IQ samples may also be filtered, amplified, attenuated, and/or resampled or interpolated to higher sample rates before and/or after being synthesized. Analog signals can be generated in other ways (eg, digital IQ samples are provided to a quadrature digital-to-analog converter that directly generates analog IF or baseband signals).

One or more of the master units 18 interface with one or more base stations 12 (additionally or alternatively) using a digital interface that interfaces with one or more base stations via an analog RF interface. can be configured to For example, master unit 18 interacts directly with one or more BBUs using the digital IQ interface used for communication between BBUs and RRHs (eg, using a CPRI serial digital IQ interface). can be configured as

On the downlink, each master unit 18 terminates one or more downlink streams of digital IQ samples provided to it from one or more BBUs and, if necessary, sends them to remote antenna units used by DAS 10. 14-compatible digital IQ sample downlink stream (by resampling, synchronizing, combining, separating, gain adjusting, etc.). On the uplink, each master unit 18 receives an uplink stream of digital IQ samples from one or more remote antenna units 14 and digitally combines the stream of digital IQ samples representing the same carrier or frequency band or subband ( by digitally summing such digital IQ samples), optionally converting them into an uplink stream of digital IQ samples compatible with one or more BBUs coupled to that master unit. (by resampling, synchronizing, combining, separating, adjusting gain, etc.).

Each master unit 18 may also be implemented in other ways.

On the downlink, each remote antenna unit 14 receives a stream of digital IQ samples from one or more master units 18, each stream of digital IQ samples representing the radio frequency spectrum output by one or more base stations 12. represents a portion of

Each remote antenna unit 14 may include, for example, one or more optical fibers or cables, one or more Ethernet compatible cables 26 (eg, one or more CAT-6A cables), or any other suitable Communicatively coupled to one or more master units 18 using a coupling medium. For example, in this embodiment each remote antenna unit 14 is connected directly via a single Ethernet cable 26, or a first Ethernet cable connects the remote antenna unit to a patch panel or expansion/intermediate unit 24; A second fiber optic cable 28 may be connected to the master unit 18 indirectly via a plurality of Ethernet compatible cables 26, such as connecting patch panels or expansion/middle units to the master unit. Each remote antenna unit 14 may be coupled to one or more master units 18 in other manners. Master unit 18 or expansion/intermediate unit 24 may also include one or more instances of power supply equipment (PSE) configured to provide power to remote antenna unit 14 .

In the exemplary DAS 10 shown in FIG. 1, a remote antenna unit 14 may have another coexisting extension unit 14 (also referred to herein as an "extended remote antenna unit") communicatively coupled thereto. It is shown. Subbing coexisting extended remote antenna units 14 from other remote antenna units 14 is done to extend the number of frequency bands radiated from that same location and/or to support MIMO services. (eg, different coexisting remote antenna units radiate and receive different MIMO streams for a single MIMO frequency band). Remote antenna unit 14 is communicatively coupled to extended remote antenna unit 14 using fiber optic cables, multi-conductor cables, coaxial cables, or the like. In such an implementation, extended remote antenna unit 14 is coupled to master unit 18 of DAS 10 via remote antenna unit 14 .

FIG. 2 is a diagram of a portion of the remote antenna unit 14 of FIG. 1, according to an embodiment in which the portion of the remote antenna unit includes one or more interference reduction circuits. As used herein, the word "reduce" includes reducing interference to non-zero values and reducing interference to approximately zero values, the latter also "removing interference ” is also called.

Remote antenna unit 14 includes one or more transmitter circuitry 40 , antenna array 42 , transmit/receive isolation circuitry 44 , analog interference cancellation circuitry 46 , control circuitry 48 , digital interference cancellation circuitry 50 , and one or more receiver circuitry 52 . include. Although the circuit diagram of FIG. 2 includes a single transmitter circuit 40 and a corresponding single receiver circuit 52, the illustrated circuit is for each additional interference-related pair of corresponding transmitter and receiver circuits. , but regardless of the number of transmitter and receiver circuits 52, it is understood that the remote antenna unit 14 may include a single antenna array 42 and a single control circuit 48. . Additionally, antenna array 42 includes a number of antennas 60 . For non-multiple-input multiple-output (non-MIMO) configurations, each antenna 60 transmits, receives, or both transmits and receives a single downlink signal or a single uplink signal at any given time. , each antenna may include one or more antenna elements configured to transmit or receive the same signal, but with respective phase shifts or respective amplitude attenuations (e.g., antennas with phased array antenna). In a MIMO configuration, each group of multiple antennas 60 within antenna array 42 is configured to transmit or receive downlink or uplink signals, and for at least the transmission period of the MIMO configuration, within the multiple antenna group. is configured to transmit a respective separate component of the MIMO downlink signal. Further, each transmitter circuit 40 may also be referred to as a downlink circuit, downlink path, transmit path, partial transmitter, etc. Similarly, each receiver circuit 52 may also be referred to as an uplink circuit, uplink path, receive It may be called a path, a partial receiver, and so on.

Each transmitter circuit 40 located on remote antenna unit 14 includes a digital-to-analog converter (DAC) 54 , a frequency upshift circuit 56 and a power amplifier 58 . DAC 54 is a digital base generated by signal processing circuitry (not shown in FIG. 2) contained in remote antenna unit 14 to include data (or other information) from base station 12 (FIG. 1). It is configured to receive a band information signal and is configured to convert the digital baseband information signal to an analog baseband information signal. Frequency upshift circuit 56 is configured to modulate the carrier signal with an analog signal, the carrier signal being in the frequency band (e.g., 3.4 GHz) in which DAS 10 (FIG. 1) is configured to operate. ~3.8 GHz). For example, portions of each transmitter circuit 40 on remote antenna unit 14 may use different carrier frequencies within the same frequency band to upshift their respective DAC output signals. Power amplifier 58 is configured to amplify the modulated carrier signal to produce a transmit signal and drive one or more antennas of antenna array 42 with the transmit signal. The digital baseband information signal may itself include or be modulated with one or more carrier signals so that the frequency upshift circuit 56 produces a DAC output signal (hereinafter upshifted carrier signal). ) is added to one or more such other carrier signals. Additionally, circuitry for transmitting downlink signals may be included entirely on the remote antenna unit 14, as transmitter circuitry 40, or included in both the remote antenna unit and the base station 12 or master unit 18. (Fig. 1). As such, transmitter circuitry 40 may include the entire transmit circuitry or may include only a portion of the transmit circuitry. In a related embodiment, transmitter circuit 40 implements a DAC using digital up-conversion (DUC). In such an embodiment, a digital upconverter (not shown in FIG. 2) is located at the input of DAC 54 and receives the baseband IQ stream and digitally upconverts (upshifts) the IQ stream to a higher frequency band. and provides the upshifted IQ stream to DAC 54 which converts the upshifted IQ stream from a digital signal to an analog signal.

Antenna array 42 includes one or more antennas 60, each of which is configured to operate as both a transmit antenna and a receive antenna (others, such as one or more embodiments described below). may include one or more transmit antennas configured for transmission only and one or more receive antennas configured for reception only). For example, antenna array 42 may be a multiple-input multiple-output (MIMO) antenna array including two or more antennas 60 . Alternatively, antenna array 42 may include only a single antenna 60 . In operation during a transmit mode, each antenna 60 of array 42 is configured to convert a transmit signal from a respective transmitter circuit 40 into a respective downlink signal, i.e., excited by the transmit signal. , each antenna radiates a respective downlink signal, eg, to user equipment 22 of FIG. If antenna array 42 is a MIMO array, the combination of the signals radiated by antennas 60 of the array can be considered a single downlink signal, but as explained below, each MIMO component transmit signal is: are considered separately for the purpose of interference cancellation. In operation during a receive mode, each antenna 60 of array 42 receives an uplink signal, eg, from user equipment 22 of FIG. 1, and converts the uplink signal to a respective received signal. If antenna array 42 is a MIMO array, the combination of signal components received by antennas 60 of the array can be considered a single uplink signal, although as explained below, each MIMO component received signal is , are processed by respective receiver circuits and considered separately for the purpose of interference cancellation.

Transmit/Receive Separation Circuit 44 is configured in the received signals from antennas 60 of antenna array 42, in particular, the transmitted signals from transmitter circuit 40 where the transmitted and received signals are simultaneous or otherwise overlap in time. configured to reduce interference caused by Because the transmit signal paths along which transmitted signals propagate from transmitter circuitry 40 to antenna array 42 may at least partially overlap the received signal paths along which received signals propagate from the antenna array to corresponding receiver circuitry 52, Portions, or components, may "leak" into the received signal. Also, since the transmitted signal is typically significantly stronger than the received signal, even a small amount of such leakage may cause the transmitted signal to "swamp" the received signal in receiver circuitry 52 . To limit such leakage to a level that is acceptable for the application, duplex isolation circuitry 44 is configured to electrically isolate receiver circuitry 52 from transmitter circuitry 40 . For example, transmit/receive isolation circuitry 44 may provide approximately 10 dB to 20 dB greater isolation than conventional isolation circuitry (eg, circulators), for example. In addition, one or more parameters of the duplex circuit 44 are, among other things, part of a closed feedback control loop in which the duplex circuit and the digital interference cancellation circuit operate to reduce transmitter interference in the received signal to the lowest achievable level. part, it may be adjustable by the digital interference cancellation circuit 50 . Additional embodiments of transmit/receive isolation circuit 44 are described in detail below in conjunction with FIGS. 7-16.

Analog interference cancellation circuitry 46 is configured to further reduce interference in the corresponding received signal to receiver circuitry 52 from a transmitted signal coupled to the same antenna 60 configured to generate the received signal. there is That is, the transmit/receive isolation circuit 44 and the analog interference cancellation circuit 46 together reduce transmit interference in the received signal to a level lower than the level of interference reduction that either of the two circuits 44 and 46 alone could provide. obtain.

The analog interference cancellation circuit 46 provides first order correction to the received signal by removing or otherwise canceling from the received signal those components of the transmitted signal that allow the transmit/receive isolation circuit 44 to leak into the received signal. can be configured to Analog interference cancellation circuitry 46 combines the correction signal with the received signal by generating an estimated first-order representation of the leaked component of the transmitted signal to appear at corresponding receiver circuitry 52 as an analog correction signal. Such first order correction may be implemented by providing an analog correction signal to receiver circuitry 52 that is configured to reduce transmit interference by combining. For example, receiver circuitry 52 may be configured to subtract an analog correction signal from the received signal to remove or otherwise cancel some or all leaked components of the transmitted signal from the received signal. Alternatively, analog interference cancellation circuitry 46 may be configured to correct for other than leakage of the transmitted signal into the received signal. For example, if the impedance of a corresponding antenna 60 of antenna array 42 does not match the effective output impedance of duplex circuit 44, this impedance mismatch causes antenna 60 to redirect a portion of the transmitted signal, Therefore, the redirected portion of the transmitted signal can be superimposed on the received signal. Additionally, a portion of the downlink signals radiated by antennas 60 of array 42 in response to transmitted signals may be reflected back to antennas 60 from objects external to remote antenna unit 14 . Therefore, the analog interference cancellation circuit 46 uses the primary analog correction signal to also consider the redirected portion of the transmitted signal and the redirected portion of the downlink signal superimposed on the received signal at the antenna 60. can be configured to generate Additionally, analog interference cancellation circuitry 46 may include or be part of one or more control loops configured to reduce transmit interference in the received signal to the lowest achievable value. Analog interference cancellation circuitry 46 is further described below in conjunction with FIGS. 3-6 and 17-19.

Control circuitry 48 is configured to control the operation of analog and digital interference cancellation circuitry 46 and 50 and may also be configured to control the operation of one or more other circuitry contained within remote antenna unit 14 . . For example, control circuitry 48 may be or include one or more microprocessors or microcontrollers. Additionally, control circuitry 48 may implement a portion or all of one or both of analog and digital interference cancellation circuitry 46 and 50 . For example, control circuitry 48 may be, include, or be arranged in a digital signal processor (DSP) or field programmable gate array (FPGA) configured to implement digital interference cancellation circuitry 50 . provided by or implemented by them.

Digital interference cancellation circuitry 50 is configured to further reduce interference in the corresponding received signal to receiver circuitry 52 from a transmitted signal coupled to antenna 60 configured to generate the received signal. . That is, transmit/receive isolation circuit 44, analog interference cancellation circuit 46, and digital interference cancellation circuit 50 together reduce the level of transmit interference in the received signal more than either of the three circuits 44, 46, and 50 alone. obtain.

The digital interference cancellation circuit 50 applies first order linear correction, and non-linear correction.

The digital interference cancellation circuit 50 generates an estimated first-order linear representation of the leaked component of the transmitted signal so that the component appears at the corresponding receiver circuit 52 as a digital correction signal, and the correction signal as It may be configured to implement such first order linear correction by providing a digital correction signal to receiver circuitry configured to reduce transmit interference by combining with the received signal. For example, the receiver circuit 52 subtracts the digital corrected signal from the analog corrected and digitized received signal so that the received signal is "passed through" the isolation circuit 44 and "arrived" by the analog interference cancellation circuit 46. can be configured to remove some or all of the leaked components of the transmitted signal. Alternatively, digital interference cancellation circuitry 50 may be configured to correct for other than leakage of the transmitted signal into the received signal. For example, the digital interference cancellation circuit 50 may, as described above in conjunction with the analog interference cancellation circuit 46, remove the redirected portion of the transmitted signal and the downlink signal superimposed on the received signal at the antenna 60. It can be configured to generate a primary digital correction signal to also take into account the redirected portion.

The digital interference cancellation circuit 50 also produces an estimated representation of the nonlinear leaky component of the transmitted signal as part of the digital correction signal so that the nonlinear leaked component appears at the corresponding receiver circuit 52. can be configured to perform the non-linear correction by . For example, one or more of DAC 54, frequency upshift circuitry 56, and power amplifier 58 of transmitter circuitry 40 may introduce non-linear components, such as total harmonic distortion, into the transmitted signal. Such nonlinear components often give rise to "skirt" signals that appear as frequency sidebands that "skirt" the transmitted signal and the corresponding downlink signal.

Digital interference cancellation circuitry 50 may be configured to perform nonlinear correction by generating, as part of the digital correction signal, an estimated representation of the nonlinear component that receiver circuitry 52 may introduce into the received signal. For example, one or more of low noise amplifier 64, frequency downshift circuit 66, and analog-to-digital converter (ADC) 68 of receiver circuit 52 introduces received signal non-linear components, such as total harmonic distortion. obtain. Such non-linear components can be combined with the non-linear components of the transmitted signal to form the aforementioned skirt signal at the output of the receiver ADC.

Each receiver circuit 52 located on remote antenna unit 14 conditions a received signal from a respective antenna 60 of antenna array 42 and provides a conditioned received signal to signal processing circuitry on remote antenna unit 14 . The signal processing circuitry is configured to provide processed received signals to base station 12 (FIG. 1) of DAS 10 . Receiver circuitry 52 includes a first signal combiner 62, eg, an adder, a low noise amplifier (LNA) 64, a frequency downshift circuit 66, an ADC 68, and a second signal combiner 70, eg, an adder. The signal combiner 62 is configured to combine the analog correction signal from the analog interference cancellation circuit 46 with the received signal from each antenna 60 of the antenna array 42, e.g. An adder configured to subtract the cancellation signal. LNA 64 is configured to amplify the once corrected received signal and frequency downshift circuit 66 is configured to downshift the once corrected received signal to the baseband frequency range. ADC 68 is configured to convert the analog baseband received signal to a digital baseband received signal, and combiner 70 is configured to combine the digital corrected signal from digital interference cancellation circuit 50 with the once corrected digital received signal. For example, combiner 70 is an adder configured to subtract the digital corrected signal from the once-corrected digital received signal to produce a twice-corrected digital received signal. . Signal processing circuitry incorporated in remote antenna unit 14 or elsewhere (e.g., master unit 18, base station 12 in FIG. 1) then converts the twice-corrected digital received signal to It is arranged to convert a number of modulated sub-carriers arranged to recover the data carried by the signal. Signal processing circuitry may include error correction circuitry and other circuitry to affect data recovery. Additionally, the circuitry for receiving uplink signals may be included entirely on the remote antenna unit 14, as receiver circuitry 52, or included in both the remote antenna unit 14 and the base station 12 or master unit 18. (Fig. 1). Thus, receiver circuitry 52 may include all of the receiver circuitry or only a portion of the receiver circuitry.

Still referring to FIG. 2, the remote antenna unit according to an embodiment in which the remote antenna unit 14 uses the same antenna 60 to receive an uplink signal while the remote antenna unit transmits a downlink signal using the antenna 60. 14 operations are described.

The base station 12 (FIG. 1) transmits signals to signal processing circuitry (not shown in FIGS. 1-2) contained in the master unit 18 or remote antenna unit 14, which is in the digital domain. is used to modulate one or more baseband carrier frequencies, and a digital time domain signal is generated from the modulated one or more carrier frequencies. For example, the signal processing circuitry may modulate the baseband carrier using 16 or 64 quadrature amplitude modulation (16-QAM, 64-QAM). Alternatively, base station 12 implements this modulation.

DAC 54 then converts the digital time domain signal from the signal processing circuitry to an analog time domain signal.

A frequency upshift circuit 56 then upshifts the analog time domain signal in frequency to the broadcast frequency band (eg, 3.4 GHz to 3.8 GHz) in which the remote antenna unit 14 is configured. Frequency upshifting circuit 56 may perform this frequency upshifting in any suitable manner, such as by modulating the carrier signal with an analog time domain signal.

Power amplifier 58 then amplifies the frequency upshifted analog time domain signal (eg, amplifies the modulated carrier signal) to produce the transmit signal.

The transmit/receive isolation circuit 44 then couples the transmit signal to the antenna 60 while reducing the magnitude of the component of the transmit signal that "leaks" to the receiver circuit 52 .

In response to being excited by the transmitted signal, antenna 60 then radiates a downlink signal that includes the data in the transmitted signal.

While antenna 60 radiates downlink signals, control circuit 48 controls analog and digital interference cancellation circuits 46 and 50 to generate analog and digital correction signals, respectively. Analog interference cancellation circuitry 46 produces analog correction signals from or otherwise in response to the transmitted signal, and digital interference cancellation circuitry 50 produces analog correction signals from or otherwise from the digital time domain signals from the signal processing circuitry. generates a digital correction signal in response. In addition, control circuitry 48 may control digital interference cancellation circuitry 50 to generate adjustment signals in duplexer circuitry 44 that reduce leakage of the transmitted signal to receiver circuitry 52 to a minimum achievable level. For example, digital interference cancellation circuitry 50 may be coupled to receiver circuitry 52 in a control loop configuration to monitor the level of transmit leakage components in the received signal or a signal derived therefrom, dither the adjustment signal, and , may determine a minimum achievable level of transmit signal leakage in the received signal or a signal derived therefrom, and then maintain the level of transmit signal leakage at or near the determined minimum achievable level. You can set the value of the adjustment signal as follows:

Antenna 60 also receives uplink signals while radiating downlink signals and converts the uplink signals to received signals.

A signal combiner 62 combines the analog corrected signal with the received signal to produce a once corrected received signal. For example, if signal combiner 62 is an adder, signal combiner 62 subtracts the analog correction signal from the received signal to produce a once corrected received signal.

A low noise amplifier 64 amplifies the once corrected received signal, and a frequency downshift circuit 66 frequency shifts (eg, demodulates) the once corrected received signal to an analog time domain received signal.

ADC 68 converts the analog time domain receive signal to a digital time domain receive signal.

A signal combiner 70 combines the digital corrected signal with the digital time domain received signal to produce a twice corrected digital time domain received signal. For example, if signal combiner 70 is an adder, signal combiner 70 subtracts the analog correction signal from the digital time domain receive signal to produce a twice corrected digital time domain receive signal.

A signal processing circuit (not shown in FIG. 2) decomposes the twice-corrected digital time-domain received signal into its data-modulated frequency components, and from the data-modulated frequency components carried by the uplink signal, recover lost data.

Reduction of first-order linear and non-linear transmit interference in data-modulated frequency components, as provided by transmit/receive separation circuit 44 and analog and digital interference cancellation circuits 46 and 50, typically includes separation circuits and interference cancellation circuits. allows the signal processing circuitry (not shown in FIG. 2) to recover the data more accurately than the signal processing circuitry omitted from the remote antenna unit 14 .

With continued reference to FIG. 2, alternate embodiments of remote antenna unit 14 are contemplated. For example, one or two of transmit/receive isolation circuitry 44 , analog interference cancellation circuitry 46 , and digital interference cancellation circuitry 50 may be omitted from remote antenna unit 14 . Further, the control circuit 48 may include or otherwise implement a digital interference cancellation circuit 50, for example, the control circuit 48 may include a microprocessor, microcontroller, FPGA, or a microprocessor, microcontroller, and FPGA. Any combination or subcombination may be configured to implement the functions and operations of the digital interference cancellation circuit 50 . Further, analog and digital interference cancellation circuits 46 and 50 may incorporate circuits or implement techniques disclosed in one or more of the following references, which are incorporated herein by reference: Jain et al. U.S. Patent Publication No. 2017/0170903, Braithwaite U.S. Patent No. 9,698,861, Braithwaite U.S. Patent No. 10,020,837, Full Duplex Radios, Bharadia et al. (2013), and IEEE 802.11-18/019 IrO. Additionally, each of the analog and digital interference cancellation circuits 46 and 50 may incorporate circuits that are modified versions of the circuits disclosed in one or more of the above references; may implement one or more techniques, each modified version of the techniques disclosed in one or more of . Additionally, the portion of transmitter circuitry 40 located on remote antenna unit 14 may be modified from that described. For example, frequency upshift circuitry 56 may be omitted and base station 12 , master unit 18 , or transmitter circuitry 40 generate a frequency upshifted analog time domain signal and provide it to power amplifier 58 . All frequency upshifting may be performed prior to the DAC 54 configured to do so. Alternatively, DAC 54 may be configured to perform some or all of the frequency upshifting of the analog time domain signal. For example, DAC 54 and frequency upshift circuit 56 may be combined into a DAC frequency upshift circuit. Additionally, the portion of receiver circuitry 52 located on remote antenna unit 14 may be modified from that described. For example, frequency downshift circuit 66 may be omitted and ADC 68, base station 12, master unit 18, or a combination or subcombination thereof, may perform all frequency downshifts of the signal from low noise amplifier 64. to produce a downshifted digital received signal. For example, ADC 68 and frequency downshift circuit 66 may be combined into an ADC frequency downshift circuit. Additionally, the topology (eg, the order of serially coupled components) of the portions of transmitter circuitry 40 and receiver circuitry 52 located on remote antenna unit 14 may be arranged in any suitable configuration. Further, in the receiver circuit 52, the LNA 64 can be located between the transmit/receive isolation circuit 44 and the signal combiner 62, rather than between the adder and the frequency downshift circuit 66, providing multiple series There may be an LNA coupled to and other circuit topologies are contemplated. Further, although described as operating in open-loop mode, analog interference cancellation circuit 46 may operate in closed-loop mode, or in both open-loop and closed-loop modes, and one You may have the above open and closed loops functioning simultaneously. Similarly, although described as operating in open-loop and closed-loop modes, digital interference cancellation circuit 50 may operate only in one or more closed-loop modes or only in one or more open-loop modes. Additionally, the embodiments described above in conjunction with FIG. 1 or below in conjunction with FIGS. 3-19 may be applicable to the remote antenna unit 14 of FIG.

FIG. 3 is a diagram of remote antenna unit 14 and analog and digital interference cancellation circuits 46 and 50 of FIG. 1, according to one embodiment. In FIG. 3, like-numbered reference items are common to FIGS. 1-3.

In the example shown in FIG. 3, the analog interference cancellation circuit 46 includes a finite impulse response (FIR) filter 80 including one or more filter paths 82 ₁ -82 _n and a signal combiner 84, eg, an adder.

Each filter path 82 includes a respective delay circuit 86 , a respective phase shift circuit 88 and a respective gain circuit 90 . Each delay circuit 86 is configured to apply a respective delay d to the transmitted signal in response to any suitable computational algorithm or It can be determined and set in advance during a calibration procedure performed while not in use for receiving. Alternatively, each delay d can be dynamically adjusted by one or more control loops built into remote antenna unit 14 . Similarly, the respective phase shift ps and the respective gain a, which each delay circuit 88 and gain circuit 90 are each configured to impart to the delayed transmitted signal, is responsive to any respective suitable computational algorithm. , or during respective calibration procedures performed while the remote antenna unit 14 is not being used to transmit or receive downlink and uplink signals. Alternatively, each of the phase shifts ps and respective gains a may be dynamically adjusted by one or more control loops built into remote antenna unit 14 . Further, the respective gain a of each amplifier 90 may be less than one, equal to one, or greater than one.

Signal combiner 84 is configured to produce an analog correction signal in response to the output signals from paths 82 ₁ -82 _n . For example, if signal combiner 84 is an adder, signal combiner 84 is configured to produce an analog correction signal equal to the sum of the output signals from paths 82 ₁ -82 _n .

Still referring to FIG. 3 , digital interference cancellation circuit 50 includes linear distortion estimator circuit 92 , nonlinear distortion estimator circuit 94 , signal combiner 96 , and separation circuit controller 98 .

Linear distortion estimator circuit 92 is configured to generate a first order linear correction signal in response to the digital time domain signal from the signal processing circuit, and nonlinear distortion estimator circuit 94 is configured to generate a first order linear correction signal in response to the same digital time domain signal. configured to generate a nonlinear correction signal;

The signal combiner 96 is configured to generate a digital correction signal in response to the first order linear and nonlinear correction signals, for example, if the signal combiner 96 is a summer, the signal combiner 96 combines the first order linear and nonlinear correction signals. It is configured to generate a digital correction signal equal to the sum of the correction signals.

Isolation circuit controller 98 is configured to generate control signals for adjusting one or more isolation characteristics or parameters of transmit/receive isolation circuit 44 in response to the first order linear and non-linear correction signals.

Still referring to FIG. 3, the remote antennas according to an embodiment in which the remote antenna unit 14 uses the same antenna 60 to receive an uplink signal at the same time that the remote antenna unit 14 transmits a downlink signal using the antenna 60. The operation of unit 14 is described.

The remote antenna unit 14 operates as described above in conjunction with FIG. 2, in addition to the operations described above in conjunction with FIG. 2, or among the operations described above in conjunction with FIG. Perform the following actions instead of one or more of:

Analog interference cancellation circuit 46 operates as follows.

Each delay circuit 86 imparts a respective delay d to the transmitted signal from transmitter circuit 40 .

Each phase shift circuit 88 imparts a respective phase shift ps to the delayed transmit signal from each delay circuit 86 on the same path 82 .

Each gain circuit 90 amplifies or attenuates the phase-shifted and delayed transmit signal from a respective phase shift circuit 88 by a respective gain a.

A signal combiner 84 produces analog correction signals in response to amplified or attenuated, phase-shifted and delayed versions of the transmit signals output from amplifiers 90 ₁ -90 _n . For example, if the signal combiner 84 is an adder, the signal combiner 84 outputs a digital signal equal to the sum of the amplified or attenuated, phase-shifted and delayed versions of the transmit signals output from the amplifiers _{90 1} -90 _n . Generate a correction signal.

Digital interference cancellation circuit 50 operates as follows.

A linear distortion estimator circuit 92 produces a linear correction signal in response to the digital time domain signal from the signal processing circuit, which is not shown in FIG. or not built-in.

A nonlinear distortion estimator circuit 94 produces a nonlinear correction signal in response to the digital time domain signal.

Signal combiner 96 produces digital correction signals in response to the linear and nonlinear correction signals from estimator circuits 92 and 94, respectively. For example, if signal combiner 96 is an adder, signal combiner 96 produces a digital correction signal equal to the sum of the linear and non-linear correction signals.

Further, isolation circuit controller 98 generates control signals for adjusting one or more isolation characteristics or parameters of transmit/receive isolation circuit 44 in response to the first order linear and non-linear correction signals. For example, the controller 98 dithers the control signal so that the transmit/receive isolation circuit 44 achieves the highest level of isolation between the transmitter circuit 40 and the receiver circuit 52, thus reducing the transmit signal to the receive signal. It may be determined and maintained to operate the transmit/receive isolation circuit 44 at the point of achieving the lowest level of leakage.

With continued reference to FIG. 3, alternate embodiments of remote antenna unit 14 are contemplated. For example, each of one or more of paths 82 of analog interference cancellation circuit 46 may lack phase shifters 88 . Additionally, the digital interference cancellation circuit 50 may lack the isolation circuit controller 98 . Additionally, the analog interference cancellation circuit 46 is described in Full Duplex Radios, Bharadia et al. or modified for inclusion in a remote antenna unit 14 configured to operate in TDD mode. Similarly, the digital interference cancellation circuit 50 is described in Full Duplex Radios, Bharadia et al. or modified for inclusion in a remote antenna unit 14 configured to operate in TDD mode. In addition, circuitry on remote antenna unit 14 communicates to one or more base stations 12 (FIG. 1) that transmitter circuitry 40 is generating transmit signals while antenna 60 is receiving uplink signals. and thereby one or more base stations 12 may direct the transmitter circuit's transmit signal generation such that the transmitter circuit's transmit signal generation does not coincide with the antenna 60 receiving the uplink signal. can be adjusted. Further, the embodiments described above in conjunction with FIGS. 1 and 2 or below in conjunction with FIGS. 4-19 may be applicable to the remote antenna unit 14 of FIG.

FIG. 4 illustrates how remote antenna unit 14 may reduce transmit interference in the received signal produced by antenna 60 ₁ of antenna array 42 from one or more other antennas 60 ₂ - 60 _n of the same antenna array. 2 is a diagram of the remote antenna unit 14 of FIG. 1, according to a constructed embodiment; FIG. In FIG. 4, like-numbered reference items are common to FIGS. 1-4.

In addition to transmitter circuit 40 _{1 ,} which is similar to transmitter circuit ₄₀ of FIGS. Each is coupled to a respective antenna 60 ₂ -60 _n of array 42, but is otherwise similar to transmitter circuit 40 ₁ .

In addition to a duplexer circuit 44 ₁ that is similar to the duplexer circuit ₄₄ of FIGS _. Each of the antenna circuits 40 ₂ -40 _n is coupled between a respective one of the antenna circuits 40 ₂ -40 n and a respective one of the antennas 60 2 -60 _n , but is otherwise similar to the transmit/receive isolation circuit 44 ₁ .

And, in addition to receiver circuit 52 ₁ which is similar to receiver circuit 52 of FIGS. 2-3, remote antenna unit 14 may include one or more other receiver circuits 52 ₂ - 52 _n ( not shown), which are each coupled to the other antennas 60 ₂ -60 _n of antenna array 42, but are otherwise similar to receiver circuit 52 ₁ .

If antenna 60 ₁ is receiving an uplink signal at the same time that one or more of the other antennas 60 ₂ - 60 _n are radiating their respective downlink signals, the downlink signals are typically , is much stronger than the uplink signal, the one or more downlink signals may be such that the received signal produced by antenna 60 ₁ is much stronger than the component of the received signal corresponding to the received uplink signal. The uplink signal will be "swamped" so that it contains some transmit interference.

Therefore, the analog interference cancellation circuit 46 is configured not only to reduce transmit interference in the received signal from the antenna 60 ₁ from the transmit signal generated by the transmitter circuit 40 ₁ , but also one or more It is also configured to reduce transmission interference from downlink signals transmitted by other antennas 60 ₂ -60 _n . Analog interference cancellation circuit 46 therefore includes a respective analog canceller circuit 102 ₁ -102 _n for each transmitter circuit 40 ₁ -40 _n , eg, each analog canceller circuit is identical to FIR filter 80 of FIG. could be. Each analog canceller circuit 102 ₁ -102 _n is configured to generate a respective component of the analog correction signal, and the signal combiner 104 is configured to generate the analog correction signal in response to the components. For example, if signal combiner 104 is an adder, signal combiner 104 produces an analog correction signal equal to the sum of the component signals from analog canceller circuits 102 ₁ -102 _n .

Similarly, digital interference cancellation circuitry 50 is configured not only to reduce transmit interference in the received signal from antenna 60 ₁ from the transmit signal generated by transmitter circuitry 40 ₁ , but also to reduce transmit interference in the signal received from antenna 60 ₁ . It is also configured to reduce transmission interference from downlink signals transmitted by one or more other antennas 60 ₂ - 60 _n in the same antenna array 42 to which it belongs. Digital interference cancellation circuit 50 therefore includes a respective digital canceller circuit 106 ₁ -106 _n for each transmitter circuit 40 ₁ -40 _n , eg, each digital canceller circuit arranged as shown in FIG. It may also include respective linear distortion estimator circuits 92 , respective nonlinear distortion estimator circuits 94 , and respective signal combiners 96 . Each digital canceller circuit 106 is configured to generate a respective component of the digital correction signal, and signal combiner 108 is configured to generate the digital correction signal in response to the components. For example, if signal combiner 108 is an adder, signal combiner 108 produces a digital correction signal equal to the sum of the component signals from digital canceller circuits 106 ₁ -106 _n . In addition, isolation circuit controller 98 is responsive to any of the component signals from digital canceller circuits 106 ₁ - 106 _n or from signals output by linear and nonlinear distortion estimator circuits 92 and 94 of each of the digital canceller circuits. to generate a control signal for the transmission/reception separation circuit 44 ₁ .

Continuing to refer to FIG. 4, while antenna 60 ₁ receives an uplink signal, remote antenna unit 14 is operated while each of one or more of transmitter circuits 40 ₁ - 40 _n generates a respective transmit signal. The operations are similar to those described above in conjunction with FIG. 2 and may be similar to the operations described above in conjunction with FIG. One or more of which replace one or more of the operations described above in conjunction with FIGS.

Analog interference cancellation circuitry 46 produces analog correction signals in response to each of the one or more transmit signals generated by respective ones of transmitter circuits 40 ₁ - 40 _n .

Digital interference cancellation circuitry 50 generates digital correction signals and isolation control signals in response to one or more digital time domain signals each generated by the signal processing circuitry.

Although not shown, in some examples analog interference cancellation circuit 46 includes a respective set of analog canceller circuits 102 for each of the other receiver circuits 52 ₂ - 52 _n , each set of analog canceller circuits , are similar in topology and operation to the set of analog canceller circuits 102 ₁ -102 _n . In another example, the analog correction signal from signal combiner 104 may be provided to each respective receiver circuit 52 .

Similarly, although not shown, in some examples digital interference cancellation circuit 50 includes a respective set of digital canceller circuits 106 for each of the other receiver circuits 52 ₂ - 52 _n , and Each set is similar in topology and operation to the set of digital canceller circuits 106 ₁ -106 _n . In another example, the digital correction signal from signal combiner 108 may be provided to each respective receiver circuit 52 .

Although not shown, in some examples, the digital interference cancellation circuit 50 includes a respective isolation circuit controller 98 for each of the other transmit/receive isolation circuits 44 ₂ - 44 _n , each isolation circuit controller 98 in topology and operation. In other examples, control signals from the isolation circuit controller 98 may be provided to multiple duplex circuits 44 .

With continued reference to FIG. 4, in an alternative embodiment, instead of or in addition to reducing transmit interference in the received signal, the remote antenna unit 14 has one or more receiver circuits 52 each of which circuitry configured to detect, while receiving, that each of one or more of transmitter circuits 40 ₁ - 40 _n is generating a respective transmit signal; It is configured to take corresponding action in response to detection. In other words, remote antenna unit 14 ensures that one or more of antennas 60 ₁ - 60 _n each transmit a respective downlink signal while at least one of the antennas also receives an uplink signal. including circuitry configured to detect that the For example, the remote antenna unit 14 may be configured to transmit a notification to one or more base stations 12 (FIG. 1) that the remote antenna unit 14 is experiencing simultaneous downlink transmission and uplink reception; In response to the notification, one or more base stations 12 coordinate transmission of downlink signals by remote antenna units 14 with reception of uplink signals by remote antenna units 14 for simultaneous transmission by remote antenna units 14 . and reception can be reduced or eliminated. Alternatively, the remote antenna unit 14 may direct each of one or more of the separate transmit/receive circuits 44 ₁ - 44 _n to each transmit signal while each of the one or more of the antennas is receiving an uplink signal. A signal may be decoupled from each of the antennas 60 ₁ -60 _n . Since this latter action can cause loss of data, the remote antenna unit 14 also instructs one or more base stations 12 to be blocked for retransmission or to retransmit otherwise lost data. Additionally, it is configured to notify one or more base stations 12 of decoupled transmissions.

With continued reference to FIG. 4, alternate embodiments of remote antenna unit 14 are contemplated. For example, the embodiments described above in conjunction with FIGS. 1-3 or below in conjunction with FIGS. 5-19 may be applicable to the remote antenna unit 14 of FIG.

FIG. 5 illustrates that a remote antenna unit may reduce transmit interference from one or more other antennas on one or more other remote antenna units in the received signal produced by antenna 60 ₁ of antenna array 42 . 2 is a diagram of the remote antenna unit 14 of FIG. 1, according to an embodiment configured in FIG. In FIG. 5, like-numbered reference items are common to FIGS. 1-5.

In addition to transmitter circuit 40 ₁ and antenna 60 ₁ , remote antenna unit 14 includes one or more “sniffer” antennas 120 ₁ -120 _m and one or more corresponding “sniffer” receiver circuits 122 ₁ -122 _m. including. As described above in conjunction with FIG. 4, the remote antenna unit 14 also includes one or more other transmitter circuits 40 ₂ -40 _n , one or more other duplex circuits 44 ₂ -44 _n , may include one or more other receiver circuits 52 ₂ - 52 _n and one or more other antennas 60 ₂ - 60 _n (these other transmitter circuits, other duplex circuits, other receiver circuitry, and other antennas are omitted from FIG. 5 for clarity).

While antenna ₆₀₁ is receiving uplink signals, each of the one or more other remote antenna units 14 (other remote antenna units 14 are not shown in FIG. 5) are transmitting respective downlink signals. If so, the downlink signal (even from another nearby remote antenna unit) is typically much stronger than the uplink signal, so one or more of the downlink signals It will "swamp" the uplink signal such that the received signal produced by antenna 60 ₁ will contain transmitted interference that is much stronger than the component of the received signal corresponding to the received uplink signal. .

Since antenna 60 (not shown in FIG. 5) on remote antenna unit 14 is typically directional at frequencies used in cellular radio communications, each sniffer antenna 120 ₁ -120 _m is a separate Each antenna 60 on the remote antenna unit 14 may have a respective orientation that increases the effective gain of the sniffer antenna. For example, the installer of DAS 10 (FIG. 1) can direct the main beams of sniffer antennas 120 ₁ -120 _m to one or more antennas 60 on other remote antenna units 14 near each other remote antenna unit 14 . Each of the sniffer antennas 120 ₁ -120 _m may be oriented in response to the location of the antenna unit 14 .

Each sniffer antenna 120 ₁ -120 _m has one or more antennas that interfere with uplink signals received by antenna 60 ₁ from respective other remote antenna units 14 (other remote antenna units are not shown in FIG. 5). It is configured to receive respective downlink signals and generate respective sniffer readout signals in response to the one or more received downlink signals.

Each sniffer receiver circuit 122 ₁ -122 _m converts a respective sniffer readout signal into a corresponding amplified sniffer readout signal suitable for input to analog interference cancellation circuitry 46 and to input to digital interference cancellation circuitry 50 . A suitable sniffer is configured to convert to a digital time domain signal. Each sniffer receiver circuit 122 ₁ -122 _m includes a respective LNA 124, a respective frequency downshift circuit 126, and a respective ADC 128, which are LNA 64 ₁ of receiver circuit 52 ₁ , frequency downshift circuit 66 ₁ , and ADC 68 ₁ , respectively, and matching LNAs 64 ₁ and 124, frequency downshift circuits 66 ₁ and 126, and ADCs 68 ₁ and 128 determines the level of transmit interference reduction that digital interference cancellation circuit 50 can provide. can be increased. For example, such matching may be achieved by placing LNAs 64 ₁ and 124, frequency downshift circuits 66 ₁ and 126, and ADCs 68 ₁ and 128 on the same integrated circuit die.

Therefore, the analog interference cancellation circuit 46 is configured not only to reduce transmit interference in the received signal from the antenna 60 ₁ from the transmit signal generated by the transmitter circuit 40 ₁ , but also one or more so as to reduce transmission interference from one or more downlink signals transmitted by one or more other antennas 60 on other remote antenna units 14 (other remote antenna units 14 are not shown in FIG. 5). is also configured. Therefore, analog interference cancellation circuitry 46, in addition to including analog cancellation circuitry 130 _m+1 for transmitter circuitry 40 ₁ , includes respective analog cancellation circuitry 130 _{1 -1} for each sniffer receiver circuitry 122 1 -122 _m . Including 130 _m . For example, each analog canceller circuit 130 ₁ -130 _m+1 can be identical to FIR filter 80 of FIG. Each analog canceller circuit 130 ₁ -130 _m+1 is configured to generate a respective component of the analog correction signal, and signal combiner 104 is configured to generate the analog correction signal in response to these components. ing. For example, if signal combiner 104 is an adder, signal combiner 104 is configured to produce an analog correction signal equal to the sum of the component signals from analog canceller circuits 130 ₁ -130 _m+1 .

Similarly, the digital interference cancellation circuit 50 is configured to reduce transmit interference in the received signal from the antenna 60 ₁ from the transmit signal generated by the transmitter circuit 40 ₁ , as well as one or more It is also configured to reduce transmission interference from downlink signals transmitted by one or more other antennas 60 on other remote antenna units 14 (other remote antenna units not shown in FIG. 5). Thus, the digital interference cancellation circuit 50 includes a respective digital canceller circuit 132 ₁ -132 _m for each sniffer receiver circuit 122 ₁ -122 _m and a digital canceller circuit 132 _m+1 for the transmitter circuit 40 ₁ , for example , each digital canceller circuit 132 ₁ -132 _m may include a respective linear distortion estimator circuit 92, a respective nonlinear distortion estimator circuit 94, and a respective signal combiner 96, arranged as shown in FIG. . Each digital canceller circuit 132 ₁ -132 _m+1 is configured to generate a respective component of the digital correction signal, and signal combiner 108 is configured to generate the digital correction signal in response to the component. . For example, if signal combiner 108 is an adder, signal combiner 108 is configured to produce a digital correction signal equal to the sum of the component signals from digital canceller circuits 132 ₁ -132 _m+1 . Further, the isolation circuit controller 98 controls the signal output from the digital canceller circuits 132 _{1 -132 m+1} or by the linear and nonlinear distortion estimator circuits 92 and 94 of each of the digital canceller circuits 132 1 -132 _m+1. is configured to generate a control signal to the transmit/receive separation circuit 44 ₁ in response to any of the component signals from.

Continuing to refer to FIG. 5, while antenna 60 ₁ receives an uplink signal, one or more on one or more other nearby remote antenna units 14 (other remote antenna units 14 are not shown in FIG. 5). The operation of the remote antenna unit 14 while each of the antennas 60 is radiating a respective downlink signal is similar to the operation described above in conjunction with FIG. 2 and in conjunction with FIGS. While the operations described above may be similar, the following operations are in addition to or replace one or more of the operations described above.

Analog interference cancellation circuitry 46 is responsive to the transmit signal generated by transmitter circuitry 40 ₁ and by respective LNAs 124 of each of one or more of one or more sniffer receiver circuitry 122 ₁ -122 _m . An analog correction signal is generated in response to each of the generated one or more amplified sniffer received signals.

Digital interference cancellation circuitry 50 is responsive to digital time domain signals from signal processing circuitry to transmitter circuitry 40 ₁ and by respective ADCs 128 of each of one or more of sniffer receiver circuitry 122 ₁ -122 _m . A digital correction signal and an isolation control signal are generated in response to each of the generated one or more digital time domain signals.

Although not shown, in some examples analog interference cancellation circuit 46 includes a respective set of analog canceller circuits 130 for each of the other receiver circuits 52 ₂ - 52 _n (not shown in FIG. 5). , each set of analog canceller circuits may be similar in topology and operation to the set of analog canceller circuits 130 ₁ to 130 _m+1 . In another example, the analog correction signal from signal combiner 104 may be provided to each respective receiver circuit 52 .

Similarly, although not shown, digital interference cancellation circuit 50 includes a respective set of digital canceller circuits 132 for each of the other receiver circuits 52 ₂ - 52 _n (not shown in FIG. 5), digital canceller circuits may be similar in topology and operation to the set of digital canceller circuits 132 ₁ to 132 _m+1 . In another example, the digital correction signal from signal combiner 108 may be provided to each respective receiver circuit 52 .

Although not shown, the digital interference cancellation circuit 50 includes a respective isolation circuit controller 98 for each of the other transmit/receive isolation circuits 44 ₂ - 44 _n (not shown in FIG. 5), each isolation circuit controller 3 is similar in topology and operation to the isolation circuit controller 98 shown and described above in conjunction with .3. In other examples, control signals from the isolation circuit controller 98 may be provided to multiple duplex circuits 44 .

With continued reference to FIG. 5, in an alternative embodiment, instead of or in addition to reducing transmit interference in the received signal from antenna 60 ₁ , remote antenna unit 14 includes receiver circuits 52 ₁ -52 _n . Each of one or more of the sniffer receiver circuits 122 ₁ -122 _m engages a respective one of the sniffer antennas 120 ₁ -120 _m while each of the one or more of them is receiving a received signal. a circuit configured to detect receiving a read signal from and to take action in response to such detection. In other words, the remote antenna unit 14 may receive one or more other nearby remote antennas while at least one of the antennas 60 ₁ -60 _n contained in the remote antenna unit 14 is receiving an uplink signal. detecting that each of one or more of antennas 60 on unit 14 (other remote antenna units 14 are not shown in FIG. 5) is transmitting a respective downlink signal, and such It includes circuitry configured to take action in response to the detection. For example, the remote antenna unit 14 may be configured to notify one or more base stations 12 (FIG. 1) that the remote antenna unit 14 is experiencing simultaneous downlink transmission and uplink reception; , one or more of the base stations 12 coordinate transmission of downlink signals by other remote antenna units 14 with reception of uplink signals by remote antenna units in the same general location or "periphery." , may reduce or eliminate simultaneous transmission and reception by multiple remote antenna units 14 . Alternatively, the remote antenna unit 14 may cause one or more of each of the duplex circuits 44 ₁ to 44 _n to operate while each of one or more of the antennas 60 ₁ to 60 _n is receiving an uplink signal. Additionally, a respective one of the receiver circuits 52 ₁ -52 _n may be decoupled from a respective one of the antennas 60 ₁ -60 _n . Since this latter action may cause loss of uplink data from one or more of the user equipments 22 (FIG. 1), the remote antenna unit 14 also detects that one or more of the user equipments 22 are blocked. It may be configured to signal the decoupled uplink signal to one or more of the user equipments 22 so that the data may be retransmitted to the remote antenna unit 14 (or another remote antenna unit 14).

With continued reference to FIG. 5, alternate embodiments of remote antenna unit 14 are contemplated. For example, the embodiments described above in conjunction with FIGS. 1-4 or below in conjunction with FIGS. 6-19 may be applicable to the remote antenna unit 14 of FIG.

FIG. 6 illustrates that remote antenna unit 14 may, in received signals generated by antenna 60 ₁ of antenna array 42, receive signals from one or more other antennas 60 ₂ - 60 _n on one or more other remote antenna units. configured to reduce transmission interference and transmission interference from one or more other antennas on one or more other remote antenna units 14 (other remote antenna units 14 are not shown in FIG. 6); 2 is a diagram of the remote antenna unit 14 of FIG. 1, according to an embodiment; FIG. In effect, therefore, the remote antenna unit 14 of FIG. 6 is a combination of the remote antenna units 14 of FIGS. 6, like-numbered reference items are common to FIGS. 1-6.

In addition to transmitter circuit 40 ₁ , remote antenna unit 14 includes one or more other transmitter circuits 40 ₂ - 40 _n (only transmitter circuits 40 ₁ and 40 _n are shown in FIG. 6), which are each coupled to a respective antenna 60 ₂ -60 _n (only antennas 60 ₁ and 60 _n are shown in FIG. 6) of antenna array 42, but are otherwise similar to transmitter circuit 40 ₁ .

Further, in addition to the duplex circuit 44 ₁ , the remote antenna unit 14 includes one or more other duplex circuits 44 ₂ - 44 _n (only the duplex circuits 44 ₁ and 44 _n are shown in FIG. 6). , which are each coupled between a respective one of transmitter circuits 40 ₂ -40 _n and a respective one of antennas 60 ₂ -60 _n , but otherwise similar to transmitter isolation circuit 44 ₁ . is.

In addition, the remote antenna unit 14 includes one or more "sniffer" antennas 120 ₁ -120 _m and one or more corresponding "sniffer" receiver circuits 122 ₁ -122 _m (sniffer antenna 120 ₁ and sniffer receiver circuit 122 1 ). ₁ is shown in FIG. 6).

And, in addition to receiver circuit 52 ₁ , remote antenna unit 14 includes one or more other receiver circuits 52 ₂ - 52 _n (not shown in FIG. 6), which are in addition to antenna array 42 . antennas 60 ₂ - 60 _n , but are otherwise similar to receiver circuit 52 ₁ .

Analog interference cancellation circuitry 46 is configured to reduce transmit interference in the received signal from antenna 60 ₁ from transmitted signals generated by transmitter circuitry 40 ₁ as well as one or more other antennas. It is also configured to reduce transmission interference from downlink signals simultaneously transmitted by 60 ₂ -60 _n .

In addition, the analog interference cancellation circuit 46 may cancel one or more signals transmitted by one or more other antennas 60 on one or more other remote antenna units 14 (other remote antenna units 14 are not shown in FIG. 6). is configured to reduce transmission interference from the downlink signal of the

Therefore, the analog interference cancellation circuitry includes a respective analog canceller circuit 140 ₁ -140 _n+m for each transmitter circuit 40 ₁ -40 _n and for each sniffer receiver circuit ₁₂₂ 1 -122 _m . For example, each analog canceller circuit 140 ₁ -140 _n+m can be identical to FIR filter 80 of FIG. Each analog canceller circuit 140 ₁ -140 _n+m is configured to generate a respective component of the analog correction signal, and signal combiner 104 is configured to generate the analog correction signal in response to the component. there is For example, if signal combiner 104 is an adder, signal combiner 104 is configured to produce an analog correction signal equal to the sum of the component signals output from analog canceller circuits 140 ₁ -140 _m+n .

Similarly, the digital interference cancellation circuit 50 is configured to reduce transmit interference in the received signal from the antenna 60 ₁ from the transmit signal generated by the transmitter circuit 40 ₁ , as well as one or more It is also configured to reduce transmission interference from one or more downlink signals transmitted by other antennas 60 ₂ -60 _n .

Digital interference cancellation circuit 50 also cancels one or more signals transmitted by one or more other antennas 60 on one or more other nearby remote antenna units 14 (other remote antenna units 14 are not shown in FIG. 6). It is configured to reduce transmission interference from these downlink signals.

Therefore, the digital interference cancellation circuit 50 includes a respective digital canceller circuit 142 ₁ -142 _n+m for each transmitter circuit 40 ₁ -40 _n and for each sniffer receiver circuit 122 ₁ -122 _m , for example , each digital canceller circuit 142 ₁ to 142 _n+m may include a respective linear distortion estimator circuit 92, a respective nonlinear distortion estimator circuit 94, and a signal combiner 96, arranged as shown in FIG. . Each digital canceller circuit 142 is configured to generate a respective component of the digital correction signal, and signal combiner 108 is configured to generate the digital correction signal in response to the components. For example, if signal combiner 108 is an adder, signal combiner 108 is configured to produce a digital correction signal equal to the sum of the component signals from digital canceller circuits 142 ₁ -142 _n+m . In addition, the isolation circuit controller 98 controls the component signals from the linear and nonlinear distortion estimator circuits 92 and 94 from the digital canceller circuits 142 ₁ to 142 _n+m or from each of the digital canceller circuits 142 ₁ to 142 _n+m. , to generate a control signal to the transmission/reception separation circuit 44 ₁ .

Continuing to refer to FIG. 6, antenna 60 ₁ is receiving an uplink signal while each of one or more of transmitter circuits 40 ₁ -40 _n is generating a transmit signal, and 1 Operation of remote antenna unit 14 while each of one or more of antennas 60 on one or more other remote antenna units 14 radiates respective downlink signals is described above in conjunction with FIGS. The operation is similar to that described and further described below.

Analog interference cancellation circuitry 46 is responsive to each of the one or more transmit signals generated by respective transmitter circuitry 40 ₁ -40 _n and to a respective one of sniffer receiver circuitry 122 ₁ -122 _m . An analog correction signal is generated in response to each of the one or more sniffer received signals generated by one.

The digital interference cancellation circuit 50 is responsive to each of one or more digital time domain signals that the signal processing circuit produces for a respective one of the transmitter circuits 40 ₁ -40 _n and the sniffer receiver. A digital correction signal and an isolation control signal are generated in response to each of one or more digital time domain signals generated by one or more of ADCs 128 ₁ -128 _m of circuits 122 ₁ -122 _m .

Although not shown, in some examples analog interference cancellation circuit 46 includes a respective set of analog canceller circuits 140 for each of the other receiver circuits 52 ₂ - 52 _n (not shown in FIG. 6). , each set of analog canceller circuits may be similar in topology and operation to the set of analog canceller circuits 140 ₁ to 140 _n+m . In another example, the analog correction signal from signal combiner 104 may be provided to each respective receiver circuit 52 .

Similarly, although not shown, in some examples, the digital interference cancellation circuit 50 may be implemented by each of the digital canceller circuits 142 for each of the other receiver circuits 52 ₂ -52 _n (not shown in FIG. 6). Each set of digital canceller circuits is similar in topology and operation to the set of digital canceller circuits 142 ₁ -142 _n+m . In another example, the digital correction signal from signal combiner 108 may be provided to each respective receiver circuit 52 .

Although not shown, in some examples, the digital interference cancellation circuit 50 includes a respective isolation circuit controller 98 for each of the other transmit/receive isolation circuits 44 ₂ - 44 _n , each isolation circuit controller having a It is similar in topology and operation to the separate circuit controller 98 shown and described together. In other examples, control signals from the isolation circuit controller 98 may be provided to multiple duplex circuits 44 .

With continued reference to FIG. 6, in an alternative embodiment, instead of or in addition to reducing transmit interference in the received signal from antenna 60 ₁ , remote antenna unit 14 includes one of receiver circuits 52 each of one or more of the transmitter circuits 40 ₁ -40 _n is generating a respective transmit signal while each of the above is receiving a receive signal; and sniffer receiver circuits 122 ₁ - 122 _m configured to detect that each of the one or more of the sniffer antennas 120 ₁ -120 _m receives a readout signal from a respective one of the sniffer antennas 120 1 -120 m, and taking action in response to the detection; In other words, the remote antenna unit 14 is configured to respond while at least one of the antennas 60 ₁ - 60 _n contained within the remote antenna unit 14 is receiving an uplink signal. Additionally, one or more of antennas 60 ₁ - 60 _n are each transmitting a respective downlink signal, and one or more other nearby remote antenna units 14 (other remote antenna units 14 are includes circuitry configured to detect that each of one or more of the upper antennas 60 (not shown in FIG. 6) is transmitting a respective downlink signal. For example, the remote antenna unit 14 may be configured to transmit a notification to one or more base stations 12 (FIG. 1) that the remote antenna unit 14 is experiencing simultaneous downlink transmission and uplink reception; In response to the notification, one or more base stations 12 may coordinate transmission of downlink signals by remote antenna units 14 with reception of uplink signals by remote antenna units 14 and downlink signals by other remote antenna units 14 . Coordinate transmission of link signals with reception of uplink signals by remote antenna units to reduce or eliminate simultaneous transmission and reception by remote antenna units 14 and by multiple remote antenna units 14 in the same "surroundings." obtain. Alternatively, the remote antenna unit 14 may provide antenna 60 ₁ to each of one or more of the duplex circuits 44 ₁ -44 _n while each of the one or more of the antennas is receiving an uplink signal. . . 60 _n or to each of one or more of the transmit/receive isolation circuits from each one of the antennas 60 ₁ to 60 _n respectively. of receiver circuits 52 ₁ -52 _n can be decoupled. Since these latter actions can cause loss of data, the remote antenna unit 14 also determines whether one or more base stations 12 have been blocked for retransmission or otherwise retransmit lost data. so that one or more base stations 12 may be notified of the decoupled transmissions and one or more user equipments 22 may transmit blocked or otherwise lost data to the remote antenna unit 14 . (or to another remote antenna unit 14) to notify one or more of the user equipments 22 of the decoupled uplink signal.

With continued reference to FIG. 6, alternative embodiments of remote antenna unit 14 are contemplated. For example, each antenna 60 is configured for use by a respective operator or service provider (eg, Verizon®, T-Mobile®, Sprint®, ATT®). In turn, this may coordinate transmission of downlink signals with reception of uplink signals to prevent simultaneous transmission and reception by the same antenna 60 . Such coordination of transmission and reception may further improve isolation between transmitter circuitry 40 and receiver circuitry 52 that share the same antenna 60, and thus one or more of the transmit and receive isolation circuitry 44 may Omissions (and omissions of one or more isolation circuit controllers 98) may be permitted. Additionally, isolation between transmitter circuitry 40 and receiver circuitry 52 may be further improved by configuring all of antennas 60 on remote antenna unit 14 for use by a single operator or service provider. , which allows the transmission of downlink signals and the reception of uplink signals such that no antenna transmits a downlink signal while the same or another antenna on remote antenna unit 14 is receiving an uplink signal. can be adjusted. Further, the embodiments described above in conjunction with FIGS. 1-5 or below in conjunction with FIGS. 7-19 may be applicable to the remote antenna unit 14 of FIG.

FIG. 7 is a diagram of the transmit/receive isolation circuit 44 ₁ of FIGS. 2-6, according to one embodiment. It is understood that each of the one or more other transmit/receive isolation circuits 44 ₂ - 44 _n (FIG. 4) may be similar to isolation circuit 44 ₁ .

The transmit/receive isolation circuit 44 ₁ includes a single pole double throw electronic switch 150 .

In the coupled state, indicated by solid lines, switch 150 is configured to couple each transmitter circuit 40 to its corresponding antenna 60 and decouple antenna 60 from its corresponding receiver circuit 52 .

And, in the coupled state, indicated by dashed lines, switch 150 is configured to couple each antenna 60 to the corresponding receiver circuit 52 and decouple the antenna 60 from the corresponding transmitter circuit 40 .

In any of the described coupling states, switch 150 is configured to reduce transmit interference in the received signal produced by antenna 60 and provided to receiver circuitry 52 .

In operation, circuitry internal to remote antenna unit 14 (FIGS. 1-6) controls the coupling state of switch 150. FIG. For example, as described above in conjunction with FIGS. 3-6, in response to commands from one or more base stations 12 (FIG. 1), circuitry causes antenna 60 to receive uplink signals, While converting the uplink signal to a receive signal for receiver circuit 52 , the switch causes the corresponding transmitter circuit 40 to decouple from antenna 60 and couple antenna 60 to the corresponding receiver circuit 52 . Or, in response to a command from one or more base stations 12 (FIG. 1), the circuitry causes antenna 60, or another antenna on the same or different remote antenna unit 14, to radiate downlink signals. during which the switch decouples the receiver circuit 52 from the antenna 60 . Alternatively, isolation circuit controller 98 (FIGS. 3-6) controls the state of switch 150 in response to one or more signals generated by digital interference cancellation circuit 50 (FIGS. 2-6).

With continued reference to FIG. 7, alternative embodiments of remote antenna unit 14 are contemplated. For example, the embodiments described above in conjunction with FIGS. 1-6 or below in conjunction with FIGS. 8-19 may be applicable to the duplex circuit 44 of FIG.

FIG. 8 is a diagram of the transmit/receive isolation circuit 44 ₁ of FIGS. 2-6, according to one embodiment. It is understood that each of one or more of the other transmit/receive isolation circuits 44 ₂ -44 _n (FIG. 4) may be similar to isolation circuit 44 ₁ .

Transmit/receive isolation circuit 44 ₁ provides antenna 60 ₁ (FIGS. _2-6 ) with transmitter circuit 40 ₁ (FIGS. 2-6) while electrically isolating receiver circuit 52 1 from transmitter circuit 40 ₁ . 6), and at the same time to couple the received signal from the same antenna 60 ₁ to the receiver circuit 52 ₁ (FIGS. 2-6). That is, the transmit/receive isolation circuit 44 ₁ enables the antenna 60 ₁ to radiate downlink signals and simultaneously receive uplink signals while reducing the interference in the received signals caused by the transmitted signals to a suitable level. do. In other words, the transmit/receive isolation circuit 44 ₁ operates while the transmitter circuit 40 ₁ is providing a transmit signal to the antenna 60 ₁ and, at the same time, the receiver circuit 52 ₁ is receiving a receive signal from the antenna 60 ₁ . , to electrically isolate the receiver circuit 52 ₁ from the corresponding transmitter circuit 40 ₁ . For example, the level of such isolation that the transmit/receive isolation circuit 44 ₁ is configured to provide may be approximately 20 dB or more.

As will be explained below, the transmit/receive separation circuit 40 ₁ works by splitting the transmit signal into a plurality of components, and by causing the components to constructively interfere at the antenna 60 ₁ , and any leakage of the transmit signal. The components are configured to provide such electrical isolation, ideally by causing them to interfere destructively in the receiver circuit 52 ₁ such that the transmitted signal power is not coupled into the receiver circuit 52 ₁ . It is

The duplexer circuit 44 ₁ includes a transmitter port 160, an antenna port 162, a receiver port 164, a first phase shift combiner 166, a transmitter end impedance or load 168, a first circulator 170, a second circulator 172, It includes a second phase shift combiner 174 , an antenna end impedance or load 176 , a third phase shift combiner 178 and a receiver end impedance or load 180 .

Transmitter port 160 is configured to couple to transmitter circuitry 40 ₁ (FIGS. 2-6) and antenna port 162 is configured to couple to antenna 60 ₁ (FIGS. 2-6) to receive Receiver port 164 is configured to couple to receiver circuitry 52 ₁ (FIGS. 2-6).

A first phase shift combiner 166 is a first path configured to phase shift a first component of a transmit signal input to transmitter port 160 by a first amount (eg, −90°). 182, a second path 184 configured to shift the phase of the second component of the transmitted signal by a second amount (eg, 0°), and any suitable resistive, reactive, or complex impedance circuit. or a terminal port 186 configured to couple to a transmitter terminal load 168, which may be a device. Further, first and second paths 182 and 184 respectively produce first and second components of the transmit signal, each having approximately the same power level.

The first circulator 170, which may be a conventional passive circulator, has a first circulator port 188 coupled to the first path 182 of the first phase shift combiner 166, a second circulator port 190, and It has a third circulator port 192 .

The second circulator 172 can be a conventional passive circulator or otherwise similar to the first circulator 170 and is coupled to the second path 184 of the first phase shift combiner 166. A first circulator port 194, a second circulator port 196, and a third circulator port 198 are connected.

For purposes of describing the structure and operation of first and second circulators 170 and 172, first and second circulators 170 and 172 will be referred to by first and second circulators 170 and 172 in the following description of operation. It is assumed to impart similar attenuation and similar phase shift to the signal so that the attenuation and phase shift applied are negligible. One way to at least approximately realize this assumption is to electrically match the first and second circulators 170 and 172, for example by forming the circulators 170 and 172 on the same integrated circuit die. be.

A second phase shift combiner 174 is configured to phase shift a first subcomponent of the first component of the transmit signal received from circulator port 190 by a first amount (eg, −90°). and a second path 200 configured to shift the phase of a second subcomponent of the first component of the transmitted signal by a second amount (e.g., 0°). It includes a path 202 and an end port 204 configured to couple the first path 200 to an antenna end load 176, which can be any suitable resistive, reactive, or complex impedance circuit or device. For example, first and second paths 200 and 202 have little, if any, power in the first subcomponent to load 176 and the second subcomponent to antenna port 162 . To generate first and second subcomponents of the first component of the transmitted signal such that the secondary components have most, but not all, of the power of the first component of the transmitted signal. It is configured.

A second phase shift combiner 174 is coupled to a second circulator port 196 of the second circulator 172 and shifts the first side of the second component of the transmitted signal by a third amount (eg, 0°). a third path 206 configured to shift the phase of the subcomponent and the phase of the second subcomponent of the second component of the transmitted signal by a fourth amount (eg, −90°); and a fourth path 208 configured to shift the . For example, third and fourth paths 206 and 208 have little, if any, power in the first subcomponent to load 176 and the second subcomponent to antenna port 162 . to generate first and second subcomponents of the second component of the transmitted signal such that the secondary component has most, but not all, of the power of the second component of the transmitted signal It is configured.

Additionally, the second path 202 of the second phase shift combiner 174 is also configured to phase shift the first component of the received signal from the antenna port 162 by a second amount (eg, 0°). and the fourth path 208 is configured to phase shift the second component of the received signal from the antenna port by a fourth amount (eg, −90°). Further, second and fourth paths 202 and 208 are configured to produce respective first and second components of the received signal having approximately the same power level.

A third phase shift combiner 178 is coupled to a third circulator port 192 of the first circulator 170 and shifts the first component of the received signal by a first amount (eg, −90°) to the first component of the received signal. A first path 210 configured to shift the phase of the subcomponent and the phase of the second subcomponent of the first component of the received signal by a second amount (eg, 0°). and configured to couple the second path 212 to a receive end load 180, which can be any suitable resistive, reactive, or complex impedance circuit or device. and a terminal port 214 . Further, first and second paths 210 and 212 have little, if any, power for the first side component to load 180 and the second side for receiver port 164 . To generate first and second subcomponents of the first component of the received signal such that the subcomponents have most, but not all, of the power of the first component of the received signal. is configured to

A third phase shift combiner 178 is coupled to a third circulator port 198 of the second circulator 172 and shifts the first side of the second component of the received signal by a third amount (eg, 0°). a third path 216 configured to shift the phase of the subcomponent and the phase of the second subcomponent of the second component of the received signal by a fourth amount (eg, −90°); and a fourth path 218 configured to shift the . Further, third and fourth paths 216 and 218 have little, if any, power for the first side component to load 180 and the second side to receiver port 164 . To generate first and second subcomponents of the second component of the received signal such that the subcomponents have most, but not all, of the power of the second component of the received signal. is configured to

Ideally, there is no leakage of the first component of the transmitted signal from the third circulator port 192 of the first circulator 170 and no leakage of the transmitted signal from the third circulator port 198 of the second circulator 172. There is no leakage of the second component.

However, in practice, such leakage may exist.

Therefore, the first path 210 of the third phase shift combiner 178 is arranged to phase shift the leaky subcomponent of the first component of the transmitted signal by a first amount (eg, −90°). , and the third path 216 is configured to phase shift the leaky subcomponent of the second component of the transmitted signal by a third amount (eg, 0°).

Continuing to refer to FIG. 8, any leaky subcomponents of the transmitted signal will destructively interfere at the receiver port 164 to reduce the interference in the received signal caused by the simultaneous transmitted signals to antenna 60 ₁ . The operation of the transmit/receive separation circuit 44 ₁ according to an embodiment will now be described. Further, in the following discussion any losses imparted by the first, second and third phase shift combiners 166, 174 and 178 and the first and second circulators 170 and 172 are ignored and the first , second and third phase shift couplers 166, 174, and 178, respectively, will be ignored by any energy coupled into end loads 168, 176, and 180 and will be added to signals propagating within the circulators by circulators 170 and 172. Any phase shifts imparted are ignored and phase shift combiners 166, 174, and 178 are assumed to impart only the phase shift they are configured to impart to the signal, and phase shift combiners 166, 174 , and 178 are assumed to split the signal input to multiple of the paths into signal components with equal power, and any received signal energy propagating from antenna port 162 to transmitter port 160 is ignored.

A transmit signal of power T from transmitter circuit 40 ₁ (FIGS. 2-6) propagates into transmitter port 160 and to first phase shift combiner 166 .

A first component of the transmit signal having power T/2 propagates along a first path 182 of the first phase shift combiner 166 which shifts the phase of the first component by an amount such as -90°. , a second component of the transmitted signal having power T/2 propagates along a second path 184 that shifts the phase of the second component by an amount such as 0°.

A first component of the transmit signal propagates from the first path 182 of the first phase shift combiner 166 to the first circulator port 188 of the first circulator 170 and from the first circulator port 188 to the first It propagates to the second circulator port 190 of the circulator 170 and from the second circulator port 190 to the second path 202 of the second phase shift combiner 174 .

A second component of the transmit signal propagates from the second path 184 of the first phase shift combiner 166 to the first circulator port 194 of the second circulator 172 and from the first circulator port 194 to the second It propagates to the second circulator port 196 of the circulator 172 and from the second circulator port 196 to the third path 206 of the second phase shift combiner 174 .

A second path 202 of the second phase shift combiner 174 couples a first subcomponent of the first component of the transmit signal with a phase shift, such as 0°, to the antenna port 162 and a second A fourth path 208 of phase shift combiner 174 couples a second subcomponent of the second component of the transmit signal with a phase shift such as -90° to antenna port 162 . Because the first path 200 and the third path 206 of the second phase shift combiner 174 each couple approximately zero energy to the end load 176, the first side of the first component of the transmitted signal The component and the second subcomponent of the second component of the transmitted signal each have a signal power of approximately T/2.

Both the first subcomponent of the first component of the transmitted signal and the second subcomponent of the second component of the transmitted signal are approximately in phase (eg, −90°) at antenna port 162 , these first and second subcomponents add constructively to "reconstruct" a transmitted signal at antenna port 162 having approximately the full transmitted signal power T.

In the manner described above, first phase shift combiner 166, first and second circulators 170 and 172, and second phase shift combiner 174 are coupled to antenna 60 ₁ (FIGS. 2-6). , effectively providing a reconstructed transmit signal with approximately the same power T as the transmit signal at transmitter port 160 . That is, the transmit/receive splitter circuit 44 ₁ couples the transmit signal from the transmitter port 160 to the antenna port 162 with relatively low signal loss.

Ideally, first circulator 170 does not couple any portion of the first component of the transmitted signal from first circulator port 188 to third circulator port 192 .

However, in actual operation, first circulator 170 may couple a leaky subcomponent of the first component of the transmitted signal from first circulator port 188 to third circulator port 192 .

A first path 210 of the third phase shift combiner 178 provides a leaky subcomponent of the first component of the transmit signal by −180° (eg, −90° from the first phase shift combiner 166, and -90° from the third phase shift combiner 178) to the receiver port 164.

Also ideally, second circulator 172 does not couple any portion of the second component of the transmitted signal from first circulator port 194 to third circulator port 198 .

However, in actual operation, second circulator 172 may couple a leaky subcomponent of the second component of the transmitted signal from first circulator port 194 to third circulator port 198 .

A third path 216 of the third phase shift combiner 178 provides a leaky subcomponent of the second component of the transmit signal to 0° (eg, 0° from the first phase shift combiner 166 and a third 3 to the receiver port 164 with a total phase shift such as 0° from the phase shift combiner 178 of 3).

Consequently, since the leaky subcomponents of the first and second components of the transmitted signal have approximately opposite phases (eg, 0° and 180°) at the receiver port 164, the leaky components are at least ideal Essentially, any leaked energy from the transmitted signals interferes destructively with each other so that they are not coupled through receiver port 164 into receiver circuitry 52 ₁ (FIGS. 2-6).

Further, in operation of splitter circuit 44 ₁ , ideally, second phase shift combiner 174 receives an input received signal having power R from antenna 60 ₁ (FIGS. 2-6) at receiver port 162. receive.

A second path 202 of the second phase shift combiner 174 shifts the phase of the first component of the received signal having power R/2 by an amount such as 0°, and the phase of the second phase shift combiner 174 is A fourth path 208 shifts the phase of the second component of the received signal, which has a power of approximately R/2, by an amount such as -90°.

A first component of the received signal propagates from the second path 202 of the second phase shift combiner 174 to the second circulator port 190 of the first circulator 170 and a second component of the received signal propagates from the second Propagates from the fourth path 208 of the two phase shift combiner 174 to the second circulator port 196 of the second circulator 172 .

A first component of the received signal passes from the second circulator port 190 to the third circulator port 192 of the first circulator 170 and from the third circulator port 192 to the first circulator port of the third phase shift combiner 178 . Propagating on path 210, the first path 210 of the third phase shift combiner 178 causes the first component of the received signal at the receiver port 164 to be -90° (e.g., the second phase shift combiner A phase shift of an amount such as −90° is applied to the first component of the received signal so as to have a total phase shift such as 0° from 174 and −90° from the third phase shift combiner 178 ).

A second component of the received signal passes from the second circulator port 196 to the third circulator port 198 of the second circulator 172 and from the third circulator port 198 to the third port of the third phase shift combiner 178 . Propagating on path 216, and a third path 216, at receiver port 164, the second component of the received signal is -90° (eg, -90° from second phase shift combiner 174 and a third A phase shift of an amount such as −90° is applied to the second component of the received signal so that it has a total phase shift of such as 0° from phase shift combiner 178 .

Consequently, since both the first and second components of the received input signal have approximately the same phase (eg, −90°) at receiver port 164, they interfere constructively, thus , at the receiver port, effectively reconstructing the received signal with approximately the total power R.

In summary, transmit/receive splitting circuit 44 ₁ constructively interferes at antenna port 162 such that antenna 60 ₁ radiates a reconstructed transmit signal of approximately full power, and in the received signal, the same antenna 60 Effectively splits the transmit signal at transmitter port 160 into multiple components that destructively interfere at receiver port 164 to reduce interference caused by simultaneous transmit signals to _one .

With continued reference to FIG. 8, alternative embodiments of transmit/receive isolation circuitry 44 ₁ are contemplated. For example, in practice, isolation circuit 44 ₁ may not be ideal, but still converts the transmitted signal from transmitter circuit 40 ₁ (FIGS. 2-6) to a suitable level of attenuation and other With distortion, it can be coupled to antenna 60 ₁ to reduce interference in the received signal to receiver circuit 52 ₁ caused by the transmitted signal to a suitable level. Further, the embodiments described above in conjunction with FIGS. 1-7 or below in conjunction with FIGS. 9-19 may be applicable to the transmit/receive isolation circuit 44 ₁ of FIG.

FIG. 9 is a graph 230 of the frequency response 232 of each circulator 170 and 172 of FIG. 8 from first circulator ports 188, 194 to second circulator ports 190, 196, according to one embodiment. According to the frequency response 232, the transmit insertion loss that the signal exhibits in the 3.4 GHz to 3.8 GHz frequency band as it propagates from the first circulator port 188, 194 to the second circulator port 190, 196 is: less than 1 dB.

FIG. 10 is a graph 240 of the frequency response 242 of each circulator 170 and 172 of FIG. 8 from second circulator port 190, 196 to third circulator port 192, 198, according to one embodiment. According to the frequency response 242, the received insertion loss that the signal exhibits in the 3.4 GHz to 3.8 GHz frequency band as it propagates from the second circulator port 190, 196 to the third circulator port 192, 198 is: less than 1 dB.

FIG. 11 is a graph 250 of the frequency response 252 of each circulator 170 and 172 of FIG. 8 from first circulator port 188, 194 to third circulator port 192, 198, according to one embodiment. According to the frequency response 252, the isolation from the first circulator port 188, 194 to the third circulator port 192, 198 ranges from greater than 30 dB to greater than 50 dB in the 3.4 GHz to 3.8 GHz frequency band.

FIG. 12 shows the first circulator port 188, 194 to the second circulator port 190 compared to the frequency response 264 of the duplexer circuit 44 ₁ of FIG. 8 from the transmitter port 160 to the antenna port 162, according to one embodiment. , 196 of each circulator 170 and 172 of _FIG . Fig. 260 is a graph 260 of the frequency response 266 of each circulator from port 188,194 to third circulator port 192,198; According to frequency responses 262, 264, 266, and 268, in the 3.4 GHz to 3.8 GHz frequency band, duplexer 44 ₁ has circulators 170, 172 between transmitter port 160 and antenna port 162. It has about the same transmit insertion loss (less than 1 dB) as it would have, but a significantly higher level than a circulator (25 dB or less) would provide between transmitter port 160 and receiver port 164. Provides isolation (greater than 30 dB).

FIG. 13 is a diagram of the transmit/receive isolation circuit 44 ₁ of FIGS. 2-6, according to another embodiment. It is understood that each of one or more of the other transmit/receive isolation circuits 44 ₂ -44 _n (FIG. 4) may be similar to isolation circuit 44i of FIG. Additionally, items common to FIGS. 8 and 13 are labeled with the same reference numerals.

The duplexer circuit 44 ₁ of FIG. 13 is similar to the duplexer circuit ₄₄ 1 of FIG. Effectively allows pre-implementation, implementation, or dynamic adjustment of the phase shifts imparted by shift combiners 166, 174, and 178. Such phase adjustment adjusts the level of electrical isolation that the transmit/receive isolation circuit 44 ₁ provides between the transmitter circuit 40 ₁ (FIGS. 2-6) and the receiver circuit 52 ₁ (FIGS. 2-6). can improve.

Adjustable phase combiner 280 can be similar to phase shift combiners 166, 174, and 178, phase shift combiner 284 and two electronically adjustable capacitors, such as varactors 288 and 290, and a phase adjuster 286 , which includes at least one control line 292 . Phase shift combiner 284 includes first, second, third, and fourth phase shift signal paths 294 , 296 , 298 , and 300 , input node 302 , and output node 304 . Additionally, adjustable phase combiner 280 may include a single control line 292 shared by capacitors 288 and 290, or may include two control lines 292, one control line for each capacitor 288 and 290. or may include more than two control lines, with one or more control lines for each capacitor 288 and 290 . In addition, at least one control line is connected to each isolation circuit controller 98 (FIGS. 2-6), control circuit 48 (FIGS. 2-6), or any remote antenna unit 14 (FIGS. 2-6). It can be coupled to other circuits.

The capacitance of capacitors 288 and 290, and hence the one or more phase shifts imparted by adjustable phase combiner 280, is reduced by one or more of the corresponding phase shifts from isolation circuit controller 98 (FIGS. 2-6). The operation of adjustable phase combiner 280 is described according to a signal controlled embodiment. Further, for purposes of the following discussion, adjustable phase combiner 280 converts the signal at input node 302 into two phases of approximately equal power that propagate along first and second paths 294 and 296, respectively. It is assumed to split the signal components and ignore any loss introduced by the adjustable phase combiner.

An input signal enters input node 302 and a first component of the input signal having power P/2 propagates along path 294 imparting a phase shift, such as -90°, to the first component.

Capacitor 288 imparts a second phase shift to the once phase-shifted first component of the input signal, the magnitude of the second phase shift being the magnitude from isolation circuit controller 98 (FIGS. 2-6). Signal controlled. For example, the second phase shift may be within an approximate range of percentages of the order of up to 10°.

Capacitor 288 converts the two-times phase-shifted first component of the input signal to a third phase-shift, such as 0°, such that the three-time phase-shifted first component of the input signal is at output node 304 . is effectively redirected to a third pathway 298 that imparts to the first component.

Similarly, a second component of the input signal having a power of approximately P/2 propagates along a second path 296 imparting a phase shift, such as 0°, to the second component of the input signal.

Capacitor 290 imparts a second phase shift to the once phase-shifted second component of the input signal, the magnitude of the second phase shift being derived from isolation circuit controller 98 (FIGS. 2-6). Signal controlled. For example, the second phase shift may be within an approximate range of percentages of the order of up to 10°.

Capacitor 290 couples the twice phase-shifted second component of the input signal to a third phase, such as −90°, such that the three-time phase-shifted second component of the input signal is at output node 304 . Effectively redirecting to a fourth path 300 that imparts a shift to the second component.

The total phase shift that the first path 294, the first capacitor 288 and the third path 298 impart to the first component of the input signal is the sum of the phase shifts that the second path 296, the second capacitor 290 and the third path 300 is equal to the total phase shift imparted to the second component of the input signal. Constructively interfere to produce a phase-shifted version of the signal.

The phase shift that capacitor 288 imparts to the first component of the input signal can be the same as the phase shift that capacitor 290 imparts to the second component of the input signal, but need not be. For example, the total phase shift imparted by the first and third paths 294 and 298 to the first component of the input signal is -92°, and the second and fourth paths 296 and 300 are the second component of the input signal. In mismatched operation, where the total phase shift imparted to the components of is −89°, then capacitor 288 is such that at output node 304 the first and second components of the input signal have the same phase, Capacitor 290 can be controlled to provide a phase shift that is offset by +3° relative to the phase shift controlled to provide.

Adjustable phase combiner 282 may have a structure, configuration, and operation similar to that of adjustable phase combiner 280 .

With continued reference to FIG. 13, according to an embodiment in which any leaky subcomponents of the transmitted signal destructively interfere at the receiver port 164 to reduce interference in the received signal caused by concurrently transmitted signals: The operation of the transmission/reception separation circuit 44 ₁ will be described. Additionally, in the following discussion, any losses imparted by phase shift combiners 166, 174, and 178, adjustable phase combiners 280 and 282, and circulators 170 and 172 are ignored and imparted to signals propagating within the circulators. Any phase shift applied is ignored, and any signal energy that phase-shift couplers 166, 174, and 178 couple into end loads 168, 176, and 180, respectively, is ignored, and the paths in the couplers are The signal supplied to multiple ones of them is assumed to be split into signal components with equal power, and any signal energy propagating from antenna port 162 to transmitter port 160 is ignored.

A transmit signal of power T from transmitter circuit 40 ₁ (FIGS. 2-6) propagates to transmitter port 160 of first phase shift combiner 166 .

A first component of the transmitted signal having power T/2 propagates along a first path 182 that shifts the phase of the first component by an amount such as −90°, and the transmitted signal having power T/2 A second component of propagates along a second path 184 that shifts the phase of the second component by an amount such as 0°.

A first component of the transmit signal propagates from the first path 182 of the first phase shift combiner 166 to the first circulator port 188 of the first circulator 170 and from the first circulator port 188 to the first It propagates to the second circulator port 190 of the circulator 170 and from the second circulator port 190 to the second path 202 of the second phase shift combiner 174 .

A second component of the transmit signal propagates from the second path 184 of the first phase shift combiner 166 to the first circulator port 194 of the second circulator 172 and from the first circulator port 194 to the second It propagates to the second circulator port 196 of the circulator 172 and from the second circulator port 196 of the second circulator 172 to the third path 206 of the second phase shift combiner 174 .

A second path 202 of the second phase shift combiner 174 couples a first subcomponent of the first component of the transmit signal with a phase shift, such as 0°, to the antenna port 162 and a second A fourth path 208 of phase shift combiner 174 couples a second subcomponent of the second component of the transmit signal with a phase shift such as -90° to antenna port 162 . Because the first path 200 and the third path 206 of the second phase shift combiner 174 each couple approximately zero energy to the end load 176, the first side of the first component of the transmitted signal The component and the second subcomponent of the second component of the transmitted signal each have a signal power of approximately T/2.

Both the first subcomponent of the first component of the transmitted signal and the second subcomponent of the second component of the transmitted signal are approximately in phase (eg, −90°) at antenna port 162 , these first and second subcomponents add constructively to "reconstruct" a transmitted signal at antenna port 162 having approximately the full transmitted signal power T.

In the manner described above, first phase shift combiner 166, first and second circulators 170 and 172, and second phase shift combiner 174 are coupled to antenna 60 ₁ (FIGS. 2-6). , effectively providing a reconstructed transmit signal with approximately the same power T as the transmit signal at transmitter port 160 . That is, the transmit/receive isolation circuit 44 ₁ effectively couples the transmit signal from the transmitter port 160 to the antenna port 162 with relatively low insertion loss.

Ideally, first circulator 170 does not couple any portion of the first component of the transmitted signal from first circulator port 188 to third circulator port 192 .

However, in actual operation, first circulator 170 may couple a leaky subcomponent of the first component of the transmitted signal from first circulator port 188 to third circulator port 192 .

Adjustable phase combiner 280, operating as described above, shifts the phase of the leaky subcomponent of the first component of the transmitted signal from circulator port 192 of first circulator 170 to −90°+θ. _cap1 , etc., which causes one or more control signals on one or more control lines 292 to cause capacitors 288 and 290 to impart leaky subcomponents of the first component of the transmit signal. is the phase shift (θ _cap1 can be positive or negative). For example, isolation circuit controller 98 (FIGS. 2-6) acts to dynamically reduce the amount of interference in the received signal output at receiver port 164 caused by the transmit signal input to transmitter port 160. One or more control signals may be generated as part of a feedback control loop that

A first path 210 of the third phase-shift combiner 178 converts the once phase-shifted leaky subcomponent of the first component of the transmitted signal to −270°+θ _cap1 (first phase-shift combiner 166 to −90°, −90°+θ _cap1 from adjustable phase combiner 280, and −90° from third phase shift combiner 178). .

Also ideally, second circulator 172 does not couple any portion of the second component of the transmitted signal from first circulator port 194 to third circulator port 198 .

However, in actual operation, second circulator 172 may couple a leaky subcomponent of the second component of the transmitted signal from first circulator port 194 to third circulator port 198 .

Adjustable phase combiner 282 , which operates as described above with respect to adjustable phase combiner 280 , extracts the leaky side of the second component of the transmitted signal from third circulator port 198 of second circulator 172 . Shifts the phase of the next component by an amount such as −90°+θ _cap2 , which means that one or more control signals on one or more control lines 310 are applied to capacitors 312 and 314 to the first phase of the transmit signal. (θ _cap2 can be positive or negative). For example, isolation circuit controller 98 (FIGS. 2-6) provides feedback in the received signal output from receiver port 164 to reduce the amount of interference caused by the transmit signal input to transmitter port 160. One or more control signals may be generated as part of the control loop.

A third path 216 of the third phase shift combiner 178 converts the once phase-shifted leaky subcomponent of the second component of the transmitted signal to −90°+θ _cap2 (first phase shift combiner 166 to 0°, adjustable phase combiner 282 to −90°+θ _cap2 , and third phase shift combiner 178 to 0°).

Consequently, where θ _cap1 =θ _cap2 , or where θ _cap1 differs from θ _cap2 to compensate for the phase difference of the paths along which leaky side components propagate, the first and second components of the transmitted signal have approximately opposite phases (e.g., -90° and -270°) at the receiver port 164, the leaky component at least ideally eliminates any leaked energy from the transmitted signal. destructively interfere with each other so that they are not coupled to the receiver circuit 52 ₁ (FIGS. 2-6) via the receiver port 164. Additionally, the control loop described above acts to dynamically vary θ _cap1 and θ _cap2 to maintain the transmit signal leakage energy at receiver port 164 at the lowest achievable level.

Further, in operation of splitter circuit 44 ₁ , ideally, second phase shift combiner 174 receives an input received signal having power R from antenna 60 ₁ (FIGS. 2-6) at receiver port 162. receive.

A second path 202 of the second phase shift combiner 174 shifts the phase of the first component of the received signal having power R/2 by an amount such as 0°, and the phase shift of the second phase shift combiner 174 is A fourth path 208 shifts the phase of the second component of the received signal, which has a power of approximately R/2, by an amount such as -90°.

A first component of the received signal propagates from the second path 202 of the second phase shift combiner 174 to the second circulator port 190 of the first circulator 170 and a second component of the received signal propagates from the second Propagates from the fourth path 208 of the two phase shift combiner 174 to the second circulator port 196 of the second circulator 172 .

A first component of the received signal propagates from second circulator port 190 to third circulator port 192 of first circulator 170 and from third circulator port 192 to adjustable phase combiner 280 .

Adjustable phase combiner 280, operating as described above, shifts the phase of the first component of the received signal by an amount such as -90° + _θcap1 , which is controlled by one or more control lines. One or more of the control signals on 292 is the phase shift that capacitors 288 and 290 impose on the first component of the received signal (θ _cap1 can be positive or negative).

A first path 210 of the third phase shift combiner 178 applies the twice phase-shifted first component of the received signal to -180° + θ cap1 at the receiver port 164 where the first component of the received signal is -180° + θ _cap1 . (0° from the second phase shift combiner 174, -90° + θ _cap1 from the adjustable phase combiner 280, and -90° from the third phase shift combiner 178). , −90°, and so on.

A second component of the received signal propagates from second circulator port 196 to third circulator port 198 of second circulator 172 and from third circulator port 198 to adjustable phase combiner 282 .

Adjustable phase combiner 282, operating as described above, shifts the phase of the second component of the received signal by an amount such as -90° + _θcap2 , which is controlled by one or more control lines. One or more control signals on 310 is the phase shift that causes capacitors 312 and 314 to impose a second component of the received signal (θ _cap2 can be positive or negative).

The third path 216 of the third phase shift combiner 178 applies the twice phase-shifted second component of the received signal to -180° + θ _cap2 at the receiver port 164 . (−90° from the second phase shift combiner 174, −90°+θ _cap2 from the adjustable phase combiner 282, and 0° from the third phase shift combiner 178). , −90°, and so on.

Consequently, because both the first and second components of the received input signal have approximately the same phase (eg, −180°) at receiver port 164, they interfere constructively, thus , effectively reconstruct the received signal with approximately the total power R at the receiver port. This assumes that θ _cap1 =θ _cap2 or that θ _cap1 and θ _cap2 equal the total phase shift experienced by the first and second components of the received signal.

In summary, the transmit/receive isolation circuit 44 ₁ constructively interferes at the antenna port 162 and the received signal from the antenna 60 ₁ so that the antenna 60 ₁ radiates a reconstructed transmit signal of approximately full power. effectively splits the transmitted signal at the transmitter port 160 into multiple components that destructively interfere at the receiver port 164 to reduce interference caused by simultaneous transmitted signals to the same antenna 60 ₁ . .

With continued reference to FIG. 13, alternate embodiments of transmit/receive isolation circuitry 44 ₁ are contemplated. For example, the values of θ _cap1 and θ _cap2 that are best for transmit interference cancellation may not be the best for reconstructing the received signal at receiver port 164 because the transmitted and received signal components traverse different paths. Yes, and vice versa. Therefore, the isolation circuit controller 98 (FIGS. 2-6), and one or more control loops including the isolation circuit controller 98, may be weighted to prioritize cancellation of transmitted interference over reconstruction of the received signal. well, or vice versa. Further, instead of being controlled by isolation circuit controller 98, adjustable phase combiners 280 and 282 are either set to fixed values during manufacture or assembly of remote antenna unit 14 (FIGS. 2-6). , or have their phase shifts set to calibrated values during a calibration procedure performed once or periodically. Further, the embodiments described above in conjunction with FIGS. 1-12 or below in conjunction with FIGS. 14-19 may be applicable to the transmit/receive separation circuit 44 ₁ of FIG.

FIG. 14 shows the frequency response 332 between the transmitter port 160 and the antenna port 162, the frequency response 334 between the antenna port 162 and the receiver port 164 of the duplex circuit 44 ₁ of FIG. 13, according to one embodiment. and a graph 330 of the frequency response 336 between the transmitter port 160 and the receiver port 164. FIG. According to frequency responses 332, 334, and 336, in the 3.4 GHz to 3.8 GHz frequency band, the duplex circuit 44 ₁ provides a relatively low (eg, approximately 0.5 dB to 1.0 dB) transmit insertion loss and relatively low receive insertion loss between the antenna and receiver ports 162 and 164, but relatively high between the transmitter and receiver ports. It provides a level of electrical isolation (eg, about 38 dB or greater).

FIG. 15 shows the first circulator port 188, 194 to the second circulator port 190 compared to the frequency response 344 of the duplexer circuit 44 ₁ of FIG. 13 from the transmitter port 160 to the antenna port 162, according to one embodiment. , 196 of each circulator 170 and 172 of _FIG . Fig. 340 is a graph 340 of frequency response 346 of each circulator 170 and 172 from port 188,194 to third circulator port 192,198; According to the frequency responses 342, 344, 346, and 348, in the 3.4 GHz to 3.8 GHz frequency band, the transmit/receive splitter circuit 44 ₁ of FIG. With loss (eg, less than 1 dB), but a significantly higher level of isolation (eg, greater than 38 dB) than a circulator (eg, 25 dB or less) would provide between transmitter port 160 and receiver port 164 )I will provide a.

FIG. 16 is a diagram of the transmit/receive isolation circuit 44 ₁ of FIGS. 2-6, according to yet another embodiment. It is understood that one or more of the other duplex circuits 44 ₂ - 44 _n may be similar to duplex circuit 44 ₁ .

Isolation circuitry 44 ₁ includes transmitter port 360 , antenna port 362 , receiver port 364 , circulator 366 , balun 368 , filter circuitry 370 , signal combiner 372 , and received signal strength indicator (RSSI) circuitry 374 .

Transmitter port 360 is configured to couple to transmitter circuitry 40 ₁ (FIGS. 2-6) and antenna port 362 is configured to couple to antenna 60 ₁ (FIGS. 2-6) to receive Receiver port 364 is configured to couple to receiver circuitry 52 ₁ (FIGS. 2-6).

Circulator 366 may be similar to circulators 170 and 172 of FIGS.

Balun 368 may be a conventional balun and is configured to generate a reference signal in response to the transmitted signal at transmitter port 360, eg, the reference signal may be a low power replica of the transmitted signal. .

Filter circuit 370 is, for example, an FIR filter, one or more of whose coefficients are controllable by RSSI circuit 374 . Filter circuit 370 may be an analog or digital filter circuit (in the latter case, filter circuit 370 may include an ADC for converting the reference signal from the analog to the digital domain, converting the filtered reference signal to digital may include a DAC for converting from the domain to the analog domain).

Signal combiner 372 combines the filtered reference signal with the received signal from antenna 60 ₁ (FIGS. 2-6) via circulator 366 to produce a transmit interference canceled received signal at receiver port 364. configured to generate For example, signal combiner 372 may be an adder circuit.

RSSI circuit 374 is configured to determine the strength of the transmitted interference canceled received signal and, in response to the determined strength, control parameters of a filtering algorithm by which filter circuit 370 filters the reference signal. there is For example, as described above, RSSI circuitry 374 is configured to control one or more coefficients of the FIR filter implemented by filter circuitry 370 .

With continued reference to FIG. 16, the operation of the transmit/receive isolation circuitry 44 ₁ is described, according to one embodiment.

Transmitter circuitry 40 ₁ (FIGS. 2-6) is at transmitter port 360, through balun 368, to circulator port 376 of circulator 366, through circulator 366 to another circulator port 378, and in response to transmit signals. generates a transmit signal that propagates to antenna 60 ₁ (FIGS. 2-6), which radiates the downlink signal.

Balun 368 produces a reference signal in response to the transmitted signal, and filter circuit 370 has one or more coefficients or one or more other parameters set by feedback signals from RSSI circuit 374. An algorithm is used to filter the reference signal.

While radiating downlink signals, antenna 60 ₁ (FIGS. 2-6) receives uplink signals and produces received signals at circulator port 378 of circulator 366 in response to the uplink signals.

The received signal propagates from circulator port 378 to circulator port 380 of circulator 366 .

Because circulator 366 is non-ideal, components of the transmitted signal leak into, eg, interfere with, the received signal.

Therefore, at circulator port 380, the received signal contains transmitted signal interference that distorts the received signal.

The distorted received signal propagates from circulator port 380 to signal combiner 372 to combine the filtered reference signal with the distorted received signal for undistorted (eg, interference canceled) reception at receiver port 364 . get the signal. Although the undistorted received signal may still contain some transmit interference, the transmit/receive isolation circuit 44 ₁ reduces the transmit interference in the received signal to a level below that of the received signal at circulator port 380 . .

In principle, the transmit/receive isolation circuit 44 ₁ conditions the distorted received signal to have the lowest achievable strength, or power, at the receiver port 364 to provide the highest achievable cancellation of transmitted interference from the received signal. works with

Consequently, the feedback loop including filter circuit 370, signal combiner 372, and RSSI circuit 374 acts to maintain the power of the received signal output from signal combiner 372 at a minimum achievable level.

When transmit circuit 40 ₁ (FIGS. 2-6) is not generating a transmit signal, the reference signal is approximately zero so that the received signal does not change substantially as it propagates through combiner 372. .

With continued reference to FIG. 16, alternate embodiments of transmit/receive isolation circuitry 44 ₁ are contemplated. For example, filter circuit 370 may be or implement any suitable filter other than an FIR filter. Additionally, balun 368 may be replaced with another suitable circuit, such as a high frequency buffer or current mirror. Further, the embodiments described above in conjunction with FIGS. 1-15 or below in conjunction with FIGS. 17-19 may be applicable to the transmit/receive separation circuit 44 ₁ of FIG.

FIG. 17 is a diagram of the remote antenna unit 14 of FIG. 1, which is similar in structure and operation to the remote antenna unit of FIG. 2, but analog interference cancellation circuitry 46 of FIG. 2, according to one embodiment. includes an optical analog interference cancellation circuit 390 instead. Additionally, like numbers refer to components common to FIGS. 2-6 and 17-19.

Analog interference cancellation circuitry 390 may include electrical and optical circuitry similar to that disclosed in US Patent Publication No. 2017/0170903 to Jain et al., which is incorporated by reference. For example, the analog interference cancellation circuit 390 includes an electro-optic converter 392 configured to convert the transmit signal from the transmitter circuit 40 ₁ from the electrical domain to the optical domain, converting the analog cancellation signal from the optical domain to the electrical domain. It includes an opto-electrical converter 394 configured to convert. In some examples, analog interference cancellation circuitry further includes an optical filter (not shown) between electro-optical converter 392 and opto-electrical converter 394 .

With continued reference to FIG. 17, alternate embodiments of transmit/receive isolation circuitry 44 ₁ are contemplated. For example, analog interference cancellation circuitry 390 may complement instead of replace analog interference cancellation circuitry 46 of FIG. Additionally, analog interference cancellation circuitry 390 may complement or replace analog interference cancellation circuitry 46 in any one or more of FIGS. Further, the embodiments described above in conjunction with FIGS. 1-16 or below in conjunction with FIGS. 18 and 19 may be applicable to the transmit/receive separation circuit 44 ₁ of FIG.

FIG. 18 is a diagram of an embodiment in which the remote antenna unit 14 is similar to the remote antenna unit 14 of FIG. 6, but has separate (eg, non-shared) transmit and receive antennas 60, according to one embodiment. 1 is a diagram of one remote antenna unit 14. FIG. That is, each antenna 60 is dedicated to either transmitting downlink signals or components thereof or receiving uplink signals. Being configured with separate transmit and receive antennas 60 improves the overall isolation between the transmit and receive antennas, thus allowing the transmit/receive isolation circuit 44 to be omitted from the remote antenna unit 14. do. Omitting the transmit/receive separation circuit 44 allows the separation circuit controller 98 to be omitted from the digital interference cancellation circuit 50 . In FIG. 18, like-numbered reference items are common to FIGS. 1-6 and FIGS.

Except for a change in operation due to the lack of splitter circuit 44 and splitter circuit controller 98, the circuitry of remote antenna unit 14 may operate in a manner similar to that described above in conjunction with FIG.

With continued reference to FIG. 18, alternative embodiments of remote antenna unit 14 are contemplated. For example, the embodiments described above in conjunction with FIGS. 1-17 or below in conjunction with FIG. 19 may be applicable to the remote antenna unit 14 of FIG.

FIG. 19 shows a remote antenna unit 14 similar to the remote antenna unit 14 of FIG. 6, but with respective shared transmit and receive antennas 60 for each operator, according to one embodiment. 2 is a diagram of remote antenna unit 14 of FIG. 1 according to an embodiment having receiver circuitry 40 and respective receiver circuitry 52. FIG. That is, each antenna 60 is dedicated to a respective operator and both transmits downlink signals or components thereof and receives uplink signals in a manner coordinated and synchronized to the operator. configured for That is, the operator synchronizes the transmission of downlink signals and the reception of uplink signals on each antenna 60 such that such transmissions and receptions do not overlap in time. Switch 400, which may be similar to switch 150 of FIG. 7, provides isolation between each receiver circuit 52 and each antenna 60 while remote antenna unit 14 is transmitting downlink signals. and configured to provide isolation between each transmitter circuit 40 and each antenna while the remote antenna unit is receiving an uplink signal. 19, like-numbered reference items are common to FIGS. 1-6 and 17-19.

With continued reference to FIG. 19, alternate embodiments of remote antenna unit 14 are contemplated. For example, the embodiments described above in conjunction with FIGS. 1-18 may be applicable to remote antenna unit 14 of FIG.

The methods and techniques described herein may be implemented in analog electronic circuits, digital electronic circuits, or in programmable processors (e.g., special purpose processors, general purpose processors such as computers, microprocessors, or microcontrollers) or other processors. may be implemented with circuitry (eg, FPGA), firmware, software, or a combination thereof. Apparatuses embodying these techniques may include suitable input and output devices, programmable processors, and storage media tangibly embodying program instructions for execution by programmable processors. A process embodying these techniques may be performed by a programmable processor to execute a program of instructions to perform desired functions by operating on input data and generating appropriate output. good. The technology advantageously receives data and instructions from a data storage system, at least one input device, and at least one output device, and outputs data and instructions to the data storage system, at least one input device, and at least one output device. It can be implemented in one or more programs executable on a programmable system including at least one programmable processor coupled to send instructions. Generally, a processor will receive instructions and data from read-only memory and/or random-access memory. Storage devices suitable for tangibly embodying computer program instructions and data include, by way of example, semiconductor memory devices such as EPROM, EEPROM, and flash memory devices; magnetic disks, such as internal hard disks and removable disks; Includes all forms of non-volatile memory, including discs and DVD discs. Any of the foregoing may be supplemented by or incorporated in a specially designed application specific integrated circuit (ASIC).

Exemplary Embodiments Example 1 is a remote antenna unit comprising: a first transmitter configured to generate at least one first transmit signal; a first antenna array comprising a configured first receiver and one or more first antennas each coupled to at least one of the first transmitter and receiver; each of at least one of the one antennas configured to radiate a respective downlink signal in response to a respective one of the at least one first transmission signals; a first antenna array, each of at least one of which is configured to generate a respective one of the at least one received signal in response to an uplink signal; and first and second interference a circuit, each coupled to a first transmitter and a receiver, and for each of the at least one received signal, the at least one first transmit signal of the one or more first antennas; interference caused by one or more of at least one downlink signal radiated by one and at least one interfering downlink signal radiated by one of the one or more other antennas a remote antenna unit comprising first and second interference circuits each configured to attenuate.

Example 2 further comprises a second transmitter and a second receiver, wherein the antenna array is coupled to the first and second transmitters and to the first and second receivers, respectively. The remote antenna unit of example 1 including a multiple-input multiple-output antenna array having at least two antennas.

Example 3 includes the remote antenna unit of Example 1 or 2, wherein the antenna array includes a single antenna.

Example 4 is the remote of any of Examples 1-3, wherein one of the first and second interfering circuits includes an isolation circuit configured to electrically isolate the receiver from the transmitter. Includes antenna unit.

Example 5 includes analog interference cancellation circuitry, wherein one of the first and second interference circuits includes analog interference cancellation circuitry configured to generate a corresponding correction signal for each received signal, and the first receiver is configured to, for each received signal, produce a respective interference-canceled received signal in response to the received signal and a corresponding correction signal Including units.

Example 6 includes an analog interference cancellation circuit configured to generate a corresponding correction signal for each received signal, wherein one of the first and second interference circuits includes an analog interference cancellation circuit configured to generate a corresponding correction signal for each received signal; The remote of any of Examples 1-5, comprising a respective signal combiner configured, for a received signal, to produce an interference-canceled received signal in response to the received signal and a corresponding correction signal Includes antenna unit.

Example 7 includes the remote antenna unit of Example 5 or 6, wherein the analog interference cancellation circuitry includes a finite impulse response filter.

Example 8 includes an electro-optic transducer configured, in response to a transmit signal, to generate an optical transmit signal, and an analog interference cancellation circuit, in response to an optical transmit signal for each received signal, a corresponding optical an optical filter configured to generate a correction signal; and an opto-electric converter configured to generate each corresponding correction signal in response to the corresponding optical correction signal. , including the remote antenna unit of any of Examples 5-7.

Example 9 includes a digital interference cancellation circuit configured to generate a corresponding correction signal for each received signal, wherein one of the first and second interference circuits includes a receiver for each an analog-to-digital converter configured to generate, for each received signal, a respective digital received signal in response to the received signal; and a remote antenna unit of any of embodiments 1-8 configured to generate respective interference-canceled received signals in response to and corresponding correction signals.

Example 10 includes a digital interference cancellation circuit configured to generate a corresponding correction signal for each received signal, wherein one of the first and second interference circuits includes a receiver for each For a received signal, an analog-to-digital converter configured to produce a respective digital received signal in response to the received signal, and an interference cancellation in response to the respective digital received signal and a corresponding correction signal. and a respective signal combiner configured to generate a combined received signal.

Example 11 is an interfering antenna array including an interfering receiver configured to process at least one interfering received signal and one or more interfering antennas, wherein the one or more interfering antennas each coupled to a receiver and each configured to generate a respective one of the at least one interfering received signal in response to one or more of the at least one interfering downlink signal an interfering antenna array, wherein each of at least one of the first and second interfering circuits is coupled to the interfering receiver, and in each of the at least one received signal, at least one 11. The remote antenna unit of any of embodiments 1-10 configured to reduce interference caused by one or more of the interfering downlink signals.

Example 12 is a second antenna array including a second transmitter configured to generate at least one second transmit signal and one or more second antennas, wherein one said second antennas each coupled to a second transmitter and producing a respective second downlink signal in response to a respective one of the at least one second transmit signal; a second antenna array configured to radiate, wherein each of at least one of the first and second interfering circuits is coupled to the second transmitter and at least 12. The remote antenna unit of any of embodiments 1-11 configured to reduce interference caused by one or more secondary downlink signals in each of the one received signals.

Example 13 includes the remote antenna unit of any of Examples 1-12, wherein the at least one transmit signal and the at least one receive signal are in the same frequency band.

Example 14 includes the remote antenna unit of any of Examples 1-13, wherein the at least one transmit signal and the at least one receive signal include at least one same frequency.

Example 15 includes the remote antenna unit of any of Examples 1-14, wherein each respective downlink signal and uplink signal are in the same frequency band.

Example 16 includes the remote antenna unit of any of Examples 1-15, wherein each respective downlink signal and uplink signal includes at least one same frequency.

Example 17 includes the remote antenna unit of any of Examples 1-16, wherein the downlink and uplink signals radiated by one of the one or more other antennas are in the same frequency band .

Example 18 is a distributed antenna system comprising a master unit and at least one remote antenna unit coupled to the master unit, each of the at least one remote antenna units generating at least one transmit signal. each transmitter configured to process at least one received signal; each receiver configured to process at least one received signal; and one or more each coupled to at least one of the transmitter and receiver antennas, each of at least one of the antennas configured to radiate a respective downlink signal in response to a respective one of the at least one transmit signal a respective antenna array, each of at least one of the antennas being configured to generate a respective one of the at least one received signal in response to an uplink signal; at least one transmit signal, at least one downlink signal radiated by one of the one or more antennas, and one or more, each coupled to a receiver and in each of the at least one received signal first and second interferers, each configured to reduce interference caused by one or more of the at least one interfering downlink signal radiated by one of the other antennas of and a distributed antenna system.

Embodiment 19 is coupled to the master unit and each configured to generate one or more respective downlink data signals and to receive one or more respective uplink data signals , further comprising at least one base station, each transmitter configured to generate a respective at least one transmission signal in response to a respective one of the one or more downlink data signals; 19. The distributed antenna system of Example 18, wherein each receiver is configured to generate a respective one of the one or more uplink data signals in response to the respective at least one received signal.

Embodiment 20 provides that at least one of the at least one base station directs each transmitter of at least one of the at least one remote antenna units to each transmitter of at least one of the at least one remote antenna units while the receiver of the same remote antenna unit is not processing received signals. only includes the distributed antenna system of Example 19 configured to generate a transmit signal.

Example 21 is an interfering antenna, wherein one of the at least one remote antenna unit includes a first interfering receiver configured to process at least one interfering received signal, and one or more interfering antennas. An antenna array with one or more interfering antennas each coupled to an interfering receiver and one of at least one interfering downlink signal from another one of the remote antenna units. interfering antenna arrays each configured to produce a respective one of the at least one interfering received signal in response to the foregoing, at least one of the first and second interfering circuits; each of which is coupled to an interfering receiver and in each of the at least one received signal by one or more of the at least one interfering downlink signal from one of the other of the remote antenna units 21. Includes the distributed antenna system of any of Examples 18-20 configured to reduce induced interference.

Example 22 is a method induced by at least one of a transmitted signal generated by a remote antenna unit and a downlink signal radiated by the remote antenna unit using a first interfering circuit reducing interference in the received signal; and further reducing interference in the received signal caused by at least one of the transmitted signal and the downlink signal with a second interference circuit; including methods.

Example 23 comprises generating a received signal with an antenna in response to an uplink signal, and coupling a transmit signal to the antenna while generating the received signal with the antenna. Further comprising the method of Example 22.

Example 24 further includes generating the received signal with the antenna, and radiating the downlink signal with another antenna while generating the received signal with the antenna; Including the method of Example 22 or 23.

Example 25 is example 22, wherein reducing interference in the received signal with the first interferometric circuit comprises electrically isolating the received signal from the transmitted signal with the first interferometric circuit 24.

Example 26 further includes generating a downlink signal in response to the different transmission signal, wherein reducing interference in the received signal generates a cancellation signal in response to the different transmission signal; and generating a corrected received signal in response to the received signal and the cancellation signal.

Example 27 reduces interference in the received signal includes generating a cancellation signal in response to the downlink signal and generating a corrected received signal in response to the received signal and the cancellation signal and the method of any of Examples 22-26.

Example 28 further includes generating a downlink signal in response to the different transmitted signal, wherein further reducing interference in the received signal comprises generating a cancellation signal in response to the different transmitted signal. and generating a corrected received signal in response to the received signal and the cancellation signal.

Example 29 further reduces interference in the received signal by generating a cancellation signal in response to the downlink signal and generating a corrected received signal in response to the received signal and the cancellation signal. and the method of any of Examples 22-28.

Example 30 is a separate transmit/receive circuit, comprising a transmitter port configured to receive a transmit signal, an antenna port configured to couple to an antenna, and a receive signal. a first signal path between a receiver port, a transmitter port and an antenna port and configured to impart a first phase shift to a first transmitted portion of a transmitted signal; a second signal path between the aircraft port and the antenna port and configured to impart approximately the first phase shift to a second transmitted portion of the transmitted signal; a transmitter port; a first leakage path between the receiver port and configured to impart a second phase shift to the first leakage portion of the transmitted signal; and the transmitter port and the receiver port. and configured to impart a third phase shift to the second leaky portion of the transmitted signal that is approximately opposite the second phase shift. Contains an isolation circuit.

Example 31 provides a method in which the first signal path comprises: a first phase shifter configured to impart a first phase shift to the first transmit portion of the transmit signal; , a second phase shifter configured to impart approximately zero phase shift, and a first circulator coupled between the first and second phase shifters, the second signal path comprising: a third phase shifter configured to impart approximately a zero phase shift to a second transmitted portion of the transmitted signal; and a third phase shifter configured to impart approximately the first phase shift to a second transmitted portion of the transmitted signal. 31. The transmit/receive isolation circuit of example 30 including a configured fourth phase shifter and a second circulator coupled between the third and fourth phase shifters.

Example 32 further comprises a first combining circuit including a first phase shifter and a third phase shifter, and a second combining circuit including a second phase shifter and a fourth phase shifter Includes the transmit/receive separation circuit of Example 31.

Example 33 has the first, second, third, and fourth phase shifters configured such that the first and second transmit portions of the transmitted signal have approximately the same signal power at the antenna ports. The transmit/receive separation circuit of Embodiment 31 or 32 is included.

Embodiment 34 further comprises a first combining circuit including a first phase shifter and a third phase shifter, and a second combining circuit including a second phase shifter and a fourth phase shifter; 34. The duplex circuit of any of embodiments 31-33, wherein the first and second combining circuits are configured such that the first and second transmit portions of the transmitted signal have approximately the same signal power at the antenna port including.

Example 35 includes a first phase shifter configured to impart a first phase shift to a first transmit portion of the transmit signal, and a first phase shifter configured to impart a first phase shift to the first transmit portion of the transmit signal. , a second phase shifter configured to impart approximately zero phase shift, a first port coupled to the first phase shifter, a second port coupled to the second phase shifter, and a receive a first circulator having a third port coupled to the machine port, the second signal path configured to impart approximately zero phase shift to the second transmitted portion of the transmitted signal. a fourth phase shifter configured to impart approximately the first phase shift to the second transmit portion of the transmit signal; and a first phase shifter coupled to the third phase shifter. a second circulator having a port of , a second port coupled to the fourth phase shifter, and a third port coupled to the receiver port Includes a transmit/receive separation circuit.

Embodiment 36 includes a first phase shifter, wherein the first leakage path is configured to impart a first portion of a second phase shift to a first leakage portion of the transmit signal; a second phase shifter configured to apply a second portion of a second phase shift to the leakage portion of one; and a first circulator coupled between the first and second phase shifters. , wherein the second leakage path comprises a third phase shifter configured to impart a first portion of a third phase shift to the second leakage portion of the transmitted signal; a fourth phase shifter configured to impart a second portion of the third phase shift to the leakage portion of 2; and a second circulator coupled between the third and fourth phase shifters. , including the transmit/receive isolation circuit of any of Examples 30-35.

Example 37 further comprises a first combining circuit including a first phase shifter and a third phase shifter, and a second combining circuit including a second phase shifter and a fourth phase shifter. Includes the transmit/receive separation circuit of Example 36.

Embodiment 38 has the first, second, third, and fourth phase shifters configured such that the first and second leakage portions of the transmitted signal have approximately the same signal power at the receiver port. , embodiment 36 or 37.

Embodiment 39 further comprises a first combining circuit including a first phase shifter and a third phase shifter, and a second combining circuit including a second phase shifter and a fourth phase shifter; 39. The duplex isolation of any of embodiments 36-38, wherein the first and second combining circuits are configured such that the first and second leakage portions of the transmitted signal have approximately the same signal power at the receiver port. Including circuit.

Embodiment 40 includes a first phase shifter, wherein the first leakage path is configured to impart a phase shift of approximately 90° to the first leakage portion of the transmit signal; a second phase shifter configured to impart a phase shift of approximately 90° to the first phase shifter, a first port coupled to the first phase shifter, a second port coupled to the antenna port, and a second a first circulator having a third port coupled to two phase shifters, such that the second leakage path imparts approximately zero phase shift to the second leakage portion of the transmitted signal. a third phase shifter configured to provide a second leaky portion of the transmitted signal with approximately zero phase shift; and a first phase shifter coupled to the third phase shifter. a second circulator having a port coupled to the antenna port, a second port coupled to the antenna port, and a third port coupled to the fourth phase shifter Contains an isolation circuit.

Example 41 illustrates a method in which the first signal path includes a first phase shifter configured to impart a first phase shift to the first transmit portion of the transmit signal; , a second phase shifter configured to impart approximately zero phase shift, a first port coupled to the first phase shifter, a second port coupled to the second phase shifter, and a second a first circulator having three ports, wherein the second signal path is configured to impart approximately zero phase shift to the second transmitted portion of the transmitted signal; and , a fourth phase shifter configured to impart approximately a first phase shift to a second transmit portion of the transmit signal; a first port coupled to the third phase shifter; a fourth phase shifter; a second circulator having a second port coupled to the shifter and a third port, the first leakage path imparting a first phase shift to the first leakage portion of the transmitted signal. and a first phase shifter coupled to the third port of the first circulator and configured to impart approximately the first phase shift to the first leakage portion of the transmitted signal. a fifth phase shifter, wherein the second leakage path is configured to impart approximately zero phase shift to the second leakage portion of the transmitted signal; and a sixth phase shifter coupled to the third port of the circulator and configured to impart approximately zero phase shift to the second leakage portion of the transmitted signal. It includes a transmission/reception separation circuit.

Embodiment 42 includes a first phase shifter, wherein the first leakage path is configured to impart a first portion of a second phase shift to a first leakage portion of the transmit signal; a second phase shifter configured to apply a second portion of the second phase shift to the leakage portion of one; and a third phase shifter of the second phase shift to the first leakage portion of the transmitted signal. and a first circulator coupled between the first and second phase shifters, wherein the second leakage path is a third phase shifter of the transmitted signal. a fourth phase shifter configured to impart a first portion of a third phase shift to the leaky portion of the transmitted signal; and a second portion of the third phase shift to the second leaky portion of the transmitted signal. and a sixth phase shifter configured to apply a third portion of the third phase shift to the second leaky portion of the transmit signal. , and a second circulator coupled between the fourth and fifth phase shifters.

Embodiment 43 comprises the second phase shifter configured to modify a second portion of the second phase shift in response to the first control signal, and the fifth phase shifter configured to modify the second phase shift. 42. The duplex circuit of embodiment 42 configured to alter the second portion of the third phase shift in response to the control signal of Example 42.

Embodiment 44 phases the first, second, third, fourth, fifth, and sixth phases such that the first and second leakage portions of the transmitted signal have approximately the same signal power at the receiver port. Including the transmit/receive separation circuit of embodiment 42 or 43, in which the shifter is configured.

Embodiment 45 comprises a first phase shifter, wherein the first leakage path is configured to impart a phase shift of approximately 90° to the first leakage portion of the transmit signal; a second electronically adjustable phase shifter configured to impart a phase shift of approximately 90° to the first leaky portion of the transmitted signal to impart a phase shift of approximately 90° to a configurable third phase shifter; a first port coupled to the first phase shifter; a second port coupled to the antenna port; and a third port coupled to the second phase shifter. a fourth phase shifter configured to impart approximately zero phase shift to the second leaky portion of the transmitted signal, the second leakage path comprising a first circulator having a fifth electronically adjustable phase shifter configured to impart a phase shift of approximately 90° to the second leaky portion and impart approximately a zero phase shift to the second leaky portion of the transmitted signal; a first port coupled to the fourth phase shifter, a second port coupled to the antenna port, and a third port coupled to the fifth phase shifter; and a second circulator having ports of .

Embodiment 46 includes a first phase shifter configured to impart a first phase shift to a first transmit portion of the transmit signal, and a first phase shifter configured to impart a first phase shift to the first transmit portion of the transmit signal. , a second phase shifter configured to impart approximately zero phase shift, a first port coupled to the first phase shifter, a second port coupled to the second phase shifter, and a second a first circulator having three ports, wherein the second signal path is configured to impart approximately zero phase shift to the second transmitted portion of the transmitted signal; and , a fourth phase shifter configured to impart approximately a first phase shift to a second transmit portion of the transmit signal; a first port coupled to the third phase shifter; a fourth phase shifter; a second circulator having a second port coupled to the shifter and a third port, the first leakage path imparting a first phase shift to the first leakage portion of the transmitted signal. and a first phase shifter coupled to the third port of the first circulator and configured to impart approximately the first phase shift to the first leakage portion of the transmitted signal. and a sixth phase shifter configurable to impart approximately the first phase shift to the first leaky portion of the transmitted signal; is coupled to a third port of the second circulator, a third phase shifter configured to impart approximately zero phase shift to the second leaky portion of the transmitted signal, and the transmitted signal a seventh electronically adjustable phase shifter configured to impart approximately a first phase shift to the second leaky portion of the transmitted signal; and approximately a zero phase shift to the second leaky portion of the transmitted signal. and an eighth phase shifter configured to apply the transmit/receive isolation circuit of any of embodiments 30-45.

Example 47 is a remote antenna unit, a transmitter configured to generate a transmitted signal; a receiver configured to process a received signal; An antenna array including one or more antennas configured to radiate respective downlink signals in response to respective ones of the at least one transmit signals, and in response to uplink signals; an antenna array and a transmit/receive isolation circuit coupled to one of the one or more antennas, a transmitter, and a receiver, configured to generate a respective one of the at least one received signal at a and wherein the transmit/receive isolation circuit is between the transmitter and the antenna and is configured to impart a first phase shift to the first transmit portion of the transmit signal. and a second signal path between the transmitter and the antenna and configured to impart approximately the first phase shift to a second transmitted portion of the transmitted signal; a first leakage path between the transmitter and the receiver and configured to impart a second phase shift to the first leakage portion of the transmitted signal; and a second leakage path configured to impart a third phase shift, approximately opposite to the second phase shift, to the second leakage portion of the transmitted signal. include.

Embodiment 48 is a distributed antenna system comprising a master unit and at least one remote antenna unit coupled to the master unit, each of the at least one remote antenna unit generating a transmit signal. a respective transmitter configured, a respective receiver configured to process received signals, and a respective antenna array comprising one or more antennas each coupled to the transmitter and receiver; , configured to emit respective downlink signals in response to respective ones of the at least one transmitted signals, and to emit respective ones of the at least one received signals in response to uplink signals. a respective antenna array and a respective demultiplexing circuit coupled to one of the one or more antennas, a transmitter, and a receiver, the demultiplexing circuit being configured to generate , between the transmitter and the antenna and a first signal path between the transmitter and the antenna and configured to impart a first phase shift to a first transmitted portion of the transmitted signal; and a second signal path between the transmitter and the receiver and configured to impart approximately the first phase shift to the second transmitted portion of the transmitted signal, and the transmitting a first leakage path between the transmitter and the receiver and a second leakage portion of the transmitted signal configured to impart a second phase shift to the first leakage portion of the signal; and a second leaky path configured to impart a third phase shift approximately opposite to the second phase shift.

Embodiment 49 is coupled to the master unit and each configured to generate one or more respective downlink data signals and to receive one or more respective uplink data signals , further comprising at least one base station, each transmitter configured to generate a respective transmission signal in response to a respective one of the one or more downlink data signals, each receiver comprises the distributed antenna system of example 48 configured to generate respective ones of the one or more uplink data signals in response to respective received signals.

Embodiment 50 is a method comprising: imparting a first phase shift to a first transmit portion of a transmit signal propagating from a transmitter to an antenna over a first transmit path; applying approximately a first phase shift to a second transmitted portion of the transmitted signal propagating from the transmitter to the antenna at and a first phase shift of the transmitted signal propagating from the transmitter to the receiver over the first leakage path. applying a second phase shift to the leaky portion; and applying a third phase shift approximately opposite to the second phase shift to the second leaky portion of the transmitted signal propagating from the transmitter to the receiver on the second leakage path. and applying a phase shift of .

Embodiment 51 causes the first and second transmit portions of the transmitted signal to have approximately the same signal power at the antenna, and causes the first and second leakage portions of the transmitted signal to have approximately the same signal power at the receiver. 51. The method of example 50, further comprising: causing signal power.

Example 52 includes the method of examples 50 or 51, further comprising electronically controlling the phase shift imparted to one of the first and second transmit portions of the transmit signal.

Example 53 includes the method of any of Examples 50-52, further comprising electronically controlling the phase shift imparted to one of the first and second leaky portions of the transmitted signal .

Example 54 includes the method of any of Examples 50-53, wherein the first phase shift is approximately 90°.

Example 55 includes the method of any of Examples 50-54, wherein the second phase shift is approximately 180° and the third phase shift is approximately 0°.

Example 56 includes the method of any of Examples 50-55, wherein the second phase shift is approximately 270° and the third phase shift is approximately 90°.

Example 57 includes generating a plurality of leaky components of a transmitted signal and destructively interfering the leaky components to reduce interference in a received signal.

Embodiment 58 is a transmit/receive isolation circuit, a transmit port configured to receive a transmit signal, a receive port configured to provide a receive signal, and a transmit port disposed between the transmit port and the receive port. a first interference path provided and configured to carry a first component of the transmitted signal; and a second interference path configured to carry a second component of the transmitted signal and condition the second component such that the second components destructively interfere with each other. Includes a transmit/receive separation circuit.

Embodiment 59 is configured so that the first interference path adjusts a first component of the transmitted signal by imparting a first phase shift to the first component of the transmitted signal; is configured to condition a second component of the transmitted signal by imparting a second phase shift to the second component of the transmitted signal that is approximately opposite the first phase shift. , including the transmit/receive isolation circuit of Example 58.

Several embodiments of the invention are described as defined by the following claims. Nevertheless, it will be understood that various modifications to the described embodiments can be made without departing from the scope and spirit of the claimed invention. Accordingly, other embodiments are within the scope of the following claims.

Claims (29)

a remote antenna unit,
a first transmitter configured to generate at least one first transmission signal;
a first receiver configured to process at least one received signal;
a first antenna array comprising one or more first antennas each coupled to at least one of said first transmitter and said receiver;
each of at least one of said first antennas configured to radiate a respective downlink signal in response to a respective one of said at least one first transmit signals;
a first antenna array, each of at least one of said first antennas configured to generate a respective one of said at least one received signal in response to an uplink signal;
first and second interference circuits coupled to the first transmitter and the receiver, respectively, and in each of the at least one received signals, the at least one first transmitted signal; at least one downlink signal radiated by one of said one or more first antennas and at least one interfering downlink signal radiated by one of said one or more other antennas first and second interferometric circuits each configured to reduce interference caused by one or more of
a remote antenna unit. a second transmitter;
a second receiver;
wherein said first antenna array comprises a multiple-input multiple-output antenna array having at least two antennas respectively coupled to said first and second transmitters and to said first and second receivers; A remote antenna unit according to claim 1. 2. The remote antenna unit of Claim 1, wherein the antenna array comprises a single antenna. 2. The remote antenna unit of Claim 1, wherein one of said first and second interfering circuits includes an isolation circuit configured to electrically isolate said receiver from said transmitter. one of the first and second interference circuits including analog interference cancellation circuitry configured to generate a corresponding correction signal for each received signal;
2. The first receiver is configured, for each received signal, to generate a respective interference-canceled received signal in response to the received signal and the corresponding correction signal. A remote antenna unit as described in . one of the first and second interference circuits including analog interference cancellation circuitry configured to generate a corresponding correction signal for each received signal;
2. The receiver comprises, for each received signal, a respective signal combiner configured to produce an interference-canceled received signal in response to the received signal and the corresponding correction signal. A remote antenna unit as described in . 6. The remote antenna unit of claim 5, wherein said analog interference cancellation circuitry includes a finite impulse response filter. The analog interference cancellation circuit is
an electro-optic transducer configured to generate an optical transmit signal in response to the transmit signal;
an optical filter configured to generate a corresponding optical correction signal in response to the optical transmit signal for each received signal;
an opto-electrical converter configured to generate each corresponding correction signal in response to the corresponding optical correction signal;
6. The remote antenna unit of claim 5, comprising: one of the first and second interferometric circuits including a digital interference cancellation circuit configured to generate a corresponding correction signal for each received signal;
the receiver includes an analog-to-digital converter configured to generate, for each received signal, a respective digital received signal in response to the received signal;
the receiver is configured to generate, for each received signal, a respective interference-canceled received signal in response to the respective digital received signal and the corresponding correction signal;
A remote antenna unit according to claim 1. one of the first and second interferometric circuits including a digital interference cancellation circuit configured to generate a corresponding correction signal for each received signal;
the receiver, for each received signal,
an analog-to-digital converter configured to generate respective digital received signals in response to said received signals;
a respective signal combiner configured to produce an interference-canceled received signal in response to the respective digital received signal and the corresponding correction signal;
2. The remote antenna unit of claim 1, comprising: an interfering receiver configured to process at least one interfering received signal;
An interfering antenna array comprising one or more interfering antennas, each coupled to the interfering receiver and one of the at least one interfering downlink signal an interfering antenna array, each configured to produce a respective one of said at least one interfering received signal in response to one or more;
each of at least one of the first and second interfering circuits coupled to the interfering receiver and in each of the at least one received signal of at least one interfering downlink signal; configured to reduce interference caused by one or more
A remote antenna unit according to claim 1. a second transmitter configured to generate at least one second transmit signal;
a second antenna array comprising one or more second antennas, each of said one or more second antennas coupled to said second transmitter; a second antenna array configured to radiate respective second downlink signals in response to respective ones of the two transmitted signals;
each of at least one of the first and second interfering circuits coupled to the second transmitter and in each of the at least one received signal the respective second downlink signal; configured to reduce interference caused by
A remote antenna unit according to claim 1. 2. The remote antenna unit of claim 1, wherein said at least one transmitted signal and said at least one received signal are in the same frequency band. 2. The remote antenna unit of claim 1, wherein said at least one transmitted signal and said at least one received signal comprise at least one same frequency. 2. The remote antenna unit of claim 1, wherein each respective downlink signal and said uplink signal are in the same frequency band. 2. The remote antenna unit of claim 1, wherein each respective downlink signal and said uplink signal comprise at least one same frequency. 2. The remote antenna unit of Claim 1, wherein the downlink signal and the uplink signal radiated by one of the one or more other antennas are in the same frequency band. A distributed antenna system,
a master unit;
at least one remote antenna unit coupled to said master unit;
each of the at least one remote antenna unit;
each transmitter configured to generate at least one transmit signal;
each receiver configured to process at least one received signal;
a respective antenna array comprising one or more antennas each coupled to at least one of said transmitter and said receiver;
each of at least one of said antennas configured to radiate a respective downlink signal in response to a respective one of said at least one transmit signal;
a respective antenna array, each of at least one of said antennas configured to generate a respective one of said at least one received signal in response to an uplink signal;
at least one transmitted signal, coupled to each of said transmitter and said receiver, and radiated by one of said one or more antennas, in each of said at least one received signal; each configured to reduce interference caused by one or more of the downlink signal and at least one interfering downlink signal radiated by one of the one or more other antennas , first and second interferometric circuits, and
distributed antenna system. at least one coupled to the master unit and each configured to generate one or more respective downlink data signals and to receive one or more respective uplink data signals; further equipped with a base station,
each transmitter configured to generate the respective at least one transmit signal in response to a respective one of the one or more downlink data signals;
each receiver configured to generate a respective one of the one or more uplink data signals in response to the respective at least one received signal;
19. Distributed antenna system according to claim 18. at least one of said at least one base station directs each transmitter of at least one of said at least one remote antenna units only while said receivers of the same remote antenna unit are not processing received signals; 20. The distributed antenna system of claim 19, configured to generate transmission signals. one of the at least one remote antenna unit comprising:
an interfering receiver configured to process at least one interfering received signal;
An interfering antenna array comprising one or more interfering antennas, each coupled to the interfering receiver and from another one of the remote antenna units an interfering antenna array, each configured to produce a respective one of said at least one interfering received signal in response to one or more of said at least one interfering downlink signal; including
Each of at least one of the first and second interfering circuits is coupled to the interfering receiver, and in each of the at least one received signal, the other one of the remote antenna units configured to reduce interference caused by one or more of the at least one interfering downlink signal from
19. Distributed antenna system according to claim 18. a method,
reducing interference in a received signal caused by at least one of a transmitted signal generated by a remote antenna unit and a downlink signal radiated by the remote antenna unit with a first interfering circuit; ,
further reducing interference in the received signal caused by at least one of the transmitted signal and the downlink signal using a second interference circuit;
A method, including generating the received signal using an antenna in response to an uplink signal; and coupling the transmit signal to the antenna while generating the received signal using the antenna. 23. The method of claim 22, further comprising: generating the received signal using an antenna;
Radiating the downlink signal using another antenna while generating the received signal using the antenna;
23. The method of claim 22, further comprising: 23. Reducing interference in the received signal using the first interferometric circuit comprises electrically isolating the received signal from the transmitted signal using the first interferometric circuit. The method described in . further comprising generating the downlink signal in response to different transmission signals;
reducing interference in the received signal,
Generating a cancellation signal in response to the different transmission signal;
generating a corrected received signal in response to the received signal and the cancellation signal;
23. The method of claim 22, comprising: reducing interference in the received signal,
generating a cancellation signal in response to the downlink signal;
generating a corrected received signal in response to the received signal and the cancellation signal;
23. The method of claim 22, comprising: further comprising generating the downlink signal in response to different transmission signals;
further reducing interference in the received signal,
Generating a cancellation signal in response to the different transmission signal;
generating a corrected received signal in response to the received signal and the cancellation signal;
23. The method of claim 22, comprising: further reducing interference in the received signal,
generating a cancellation signal in response to the downlink signal;
generating a corrected received signal in response to the received signal and the cancellation signal;
23. The method of claim 22, comprising:

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